Do a search sometime on the CanLII website
as the keyword and start reading through the appeal transcripts for refused applications where people who have previously immigrated to Canada have tried to sponsor spouses and dependent children that they conveniently "forgot" to include in their applications when they immigrated because they felt those family members might somehow interfere with their approval. It's pretty pathetic.
Frankly, to require a medical exam for the non-accompanying dependent child of a spousal applicant (and especially to require forfeiture of the right to ever sponsor that child in the future if the exam is not completed) is ridiculous - because spousal applicants and their dependent children are excessive demand exempt. The results of the medical examination have absolutely no bearing on the admissibility of a spousal applicant anyway - and there are so many instances where applicants are not able to convince their ex partners (or their children) to get an exam. I even know of one applicant whose application was recently refused because his ex refused to allow their child (designated non-accompanying) to undergo examination. I was interested in what paragraph of the Act was used to justify that refusal but, unfortunately, he never responded to my inquiry.
So, it's understandable that this issue is a controversial one . . . unfortunately, doesn't look like the requirement is going to change anytime soon.
If you look at reports in CanLii the persons who "forgot" spouses and children emigrated in the skilled worker class where excessive demand is an issue, and after "landing" tried to sponsor. Also a high no. of the cases are children that were not declared in spousal applications because there was a very good chance that CIC/CHC would have queried the relationship.