Yes it is true. For example, if you live with your family and buy another property just for the investment, this property is not your principal residence.
I was speaking in general, but you were right.
Regardless you live or not , isn't your property capital will be tax free ?
Say you buy house in Alberta then move to US or even Toronto for job, there you rent and live , so whatever rental income you getting from your own house that will be taxable but whatever rent you paying that money will nullified that income . So from where it can be taxed ? Plus capital investment is never taxable if it your first and only property , regardless you live or not. Profit/Capital gains is taxable but if you go to accountant he will give you way to save that too.
In short - Google "local accountants" , pay then $ 50 for first 30 min consultancy. They will tell you what will be there fee and will save max tax . It's easy for them .