WHAT IS FOR-SURE:
There is NO doubt that the applicant must provide a current "home" address (this is item 7 in the CIT 0002 (10-2020) version of the application).
There is NO doubt that the applicant is required to "advise" IRCC if that information changes. The applicant must sign the verification (in the application form) that states:
I agree to advise Immigration, Refugees and Citizenship Canada (IRCC) if any information on this form changes before I take the Oath of Citizenship.
Additionally, the instructions clearly state:
While we process your application, contact us if any information on your application changes or if you
- change your address
- plan to leave Canada for more than 2 weeks in a row
- can’t check your application status online and the normal processing time for your application has passed
- are charged with a crime
Any claim that these are not the current, applicable instructions is NOT true. Misinformation.
WHAT THIS MEANS:
In regards to the applicant's responsibilities it is not complicated: It is not confusing or vague or ambiguous. Sure, some people will fudge what they say is their "home" address, and more than a few get away-with-it, but IRCC is clearly asking for the address where the individual lives. And if that changes any time prior to taking the oath, IRCC requires the applicant to notify IRCC of the change.
What's the point? Why is the applicant required to provide this information? Second-guessing why IRCC is asking for particular information tends to be a distraction, and especially so here where it is clear IRCC requests this information. Whatever IRCC's reasons, IRCC clearly requires applicants to advise them of changes in address.
In regards to potential consequences for not following the instructions, that is more complicated, and can vary considerably with whether that is simply a failure to follow a particular instruction, or whether it appears to be evasive or deceptive to a degree that affects a processing agent's assessment of the applicant's credibility, or constitutes a misrepresentation (which can be by omission as much as overtly giving false information). The potential consequences also vary and can be difficult to predict depending on the extent to which some people get-away-with-it (including fudging information or even making outright misrepresentations). No consequence if the person does not get caught. (Caution: misrepresentations made during the process can be grounds for revoking citizenship, for which there is no statute of limitations.)
The consequences can also vary depending on the importance of the information. For example, applicants who travel abroad for more than two weeks without notifying IRCC, who are otherwise continuing to live at the same address, will likely face NO consequences for this unless they happen to miss a notice from IRCC and fail to respond on time or show up for a scheduled event.
Otherwise, IRCC generally considers ALL its requests to be for "relevant" information. That is, if IRCC asks for it, it is considered "relevant." The more important distinction is whether the information is "material." The latter is more important because false or misleading information, including by omission, that is "material" is a stand alone ground for denying the application and invoking a prohibition for years, and if considered serious enough, can be grounds for criminal prosecution with severe penalties.
It appears much of your post is, in effect, asserting that a change in the applicant's home address after applying does not affect any of the requirements for citizenship, and therefore a failure to notify IRCC of the change is not a "material" misrepresentation. What constitutes "material" information is a very weedy subject, too weedy to go chasing that tangent far, here, BUT best to be aware the scope of what is considered to be "material" is significantly broader than information directly affecting the outcome. I will not venture to guess how misinformation about an applicant's home address will be handled in a particular case, but the risk is real that if IRCC concludes the applicant has intentionally been misleading about their home address that could be considered to be a material misrepresentation invoking the severe consequences for this . . . and, at the least, is for sure considered relevant information and if misleading or false which could severely compromise the applicant's credibility, and thus have a serious negative impact on how things go.
What This Does Not Mean:
Actual outcomes will vary, so this does not mean a failure to properly advise IRCC of a change of address will necessarily have a negative impact at all, let alone a severely negative impact. As oft noted, fudging home address information appears to be rather common and rather commonly NOT a problem.
But it does not mean there will not be a problem. Just the potential for compromising the applicant's credibility looms large.
In Regards to Passport Shopping:
Personal views aside, I mention this as a factor that can influence how things go for an applicant. The appearance of being a person who is passport-shopping or seeking-a-passport-of-convenience can trigger elevated scrutiny, non-routine processing, and even suspicions about the applicant's credibility. This is about how a total stranger bureaucrat might perceive the applicant and the influence that perception can have in how things go. Whether it should be this way is not for me to wrangle over. There are plenty of examples of applicants labouring with extra-long processing who quite likely fit the bill. This is about how it is. Which prospective applicants and those with applications in process deserve to know about, so they can make informed decisions for themselves.
By the way, there is nothing contrary to the law if a processing agent or citizenship officer decides to issue full blown RQ just based on a suspicion the applicant is someone passport-shopping or seeking-a-passport-of-convenience. Another weedy subject I have addressed in other topics. Just because the law allows otherwise qualified applicants to obtain a grant of citizenship even though they are passport-shopping, or seeking-a-passport-of-convenience, does not mean officers or agents must overlook their suspicions that such individuals may not be entirely truthful in the information they have provided, suspecting that the applicants' intentions suggest motive and an increased risk of not following the rules. Moreover, decisions to impose RQ are not reviewable.
OVERALL, it is simply wrong to give false reassurances that there will be NO problem when, in reality, applicants who live abroad while the application is pending clearly face more risks of problems arising than comparably qualified applicants who remain in Canada pending processing. The nature and scope of those risks varies. The logistical risks, for example, vary considerably depending on where in the world the applicant has relocated. Lot easier to make a short-noticed scheduled event from the States or Western Europe than it can be from various other places in the world. The procedural risks, like the possibility of RQ, also vary, depending on many other factors in the particular applicant's situation.