The dollar is likely a factor, as you mention. But from their list of cities only Toronto has a crisis of home affordability. Montreal is still within sane levels and Waterloo is not too much worse.
I live in the Waterloo region and affordability is questionable. Not terrible for most tech workers, but definitely not great for the "working class". All of Canada is in a serious housing bubble, but definitely worse in Toronto and Vancouver.
Rents in Montreal are going up but still no where near Toronto level. Cost of living is lower too on many levels. Of course it depends on the area but generally it's reasonable.
You can live pretty comfortably on a 75k salary and lots of people in the tech sector make more than this, infosec paying even 6 figures in some places.
I recently turned down an offer from Google for a job in Sunnyvale because even though I might have been paid twice as much, I knew the cost of living was much higher and quality of life probably not as good.
Montreal has a crazy-low cost of living for what is otherwise a fantastic city. Been there three times now and all were grand.
Part of it is that QC has crazy high taxes, which drives down demand and keeps the big money in VAN or YYZ, and also that there are a lot of open / in demand jobs in the QC. They offer decent salaries -- but they want people who are bilingual or purely Francophone. I get weekly notices from LinkedIn for Data Center Mgmt roles around MTL -- HydroQuebec = cheap power and therefore cheap colo -- but I don't speak enough French.
Pretty soon, rent is going to be too high for someone making 100k Canadian ( if it isn’t already )