The situation isn't unique to Calgary. It is the same in a lot of other urban centres (like Oakland) where there was no development focus on anything other than head offices and high rises.
Compare Calgary to Vancouver (I live in C and spent 20+ years in V) where there was some effort to make the downtown a more livable space. I think the downtown here in Calgary is ghastly. Loud. Ugly. Who would want to spend any time in it?
I used to walk around downtown Vancouver all the time. Never do that here.
For decades the governments running Calgary, and Alberta, have not really given a shit about anyone other than large businesses (and their campaign funding) and those businesses have done what they normally do and moved elsewhere once things got tough or they got a better deal.
And, as usual, taxpayers and residents are left with the remains once the party is over and businesses have moved on.
In this case the city has an unliveable downtown filled with skyscrapers no-one wants to move into.