The striking part of the linked story is they didn't ask anyone why they don't want to live there, or why they moved away, etc. Just "tax rates always go up and after redevelopment rents will go up even more and I have no idea why nobody is here".
Maybe they have a severe crime problem, or the commute is unbearable, or there's no public transit, or the city council makes bars close at 8pm so young adults can't party. There's plenty of examples from other cities of how to kill a downtown, I'm just curious what Calgary did specifically. Every city in the world has tax problems and redevelopers pushing rents upward. Whats special about Calgary is ... (maybe answer is 'nothing' which is itself the problem?)