In 2016, 13.5% of those between 30-34 lived with their parents, and it's been rising.
Also in 2011, 73% of 25-29 year olds have never been married where in 1981 it was 26%. I mean, how can you marry when you can't even get a place of your own? How will people even seriously think about having kids if having a home of their own becomes more and more of a pipe dream?
While I think this is an issue, I think it's a minor one. If it was a big problem, we'd see a whole bunch of 2 storey apartments sprinkled amongst single family homes. But I've never seen one in all my time in Toronto. Because there's a whole ton of regulations that make it impossible by just plain making it illegal without jumping through a whole ton of other hoops that make it far too expensive.
I'm not saying fixing this won't help, but it's just one of dozens of issues, and a minor one compared to some of them.