I wonder how much climate is playing a factor in Vancouver's issues. Just from my perspective, I'd love to move to Vancouver, but would never, ever consider Montreal, not because it's not a beautiful city, but because of the harsh winters.
Other people don't seem to really care about weather extremes or scenery, etc. I have no insight into these real estate investors dumping money into property, sure if they aren't living there, there's some other factors involved.
I'd argue climate plays a bigger factor for people who actually want to live in Vancouver, rather than absentee investors.
That said, having grown up in Vancouver, I'd consider Montreal - seeing the sun in the fall/winter is a really nice concept I've gotten used to. I've gotten used to harsh cold of the east coast, but I never got used to the dreary vast grayness even though I spent most of my childhood in it.
Keep in mind that some people also like the climate of places like Vancouver. I would count myself among them. I moved from Dublin to San Diego (supposedly known for nice weather, somehow) and the weather here is awful; I can't do anything outside without becoming a sweaty mess 9 months of the year. Apparently it's been like this the last several years in a row, possibly indicating a substantial change in the norm, but people lie to themselves about how it's always pleasant here even while it's 90F.
Other people don't seem to really care about weather extremes or scenery, etc. I have no insight into these real estate investors dumping money into property, sure if they aren't living there, there's some other factors involved.