Toronto and other cities have a large stock of rental apartment buildings built from 1950 to 1980 - increasingly these buildings are occupied by people in poverty
Most "affordable" housing projects the province and federal government fund are new buildings - these buildings are expensive and only 25%-30% of the units are actually subsidized and the rest rent at market rates.
Meanwhile CHMC provided low interest mortgages to companies that buy up apartment buildings. Providing housing vouchers or subsidies to people on fixed incomes would only be more money going into the pockets of landlords. And rent control currently only affects people once they are tenants and landlords can ask any rent they want for new tenants.
In the long run, it makes sense for governments to just help non-profits to buy up the existing rental buildings. Government, in return for their help and low interest rates, would have the right to buy the land at the end of the mortgage, or even better yet, government would get title to the land and the non-profits would own the building and have a ground lease.
This way, if ever the building is sold or should be redeveloped, the real value in the land still accrues to the public and not to non-profit groups who might use the financial gain for religious or other purposes that only benefit a few people.