Here's a link from an article I remember reading a few months ago that caught me by surprise as well. https://m.huffingtonpost.ca/2018/07/24/toronto-best-city-tec...
If you look behind the stories and check on which company's blog or who wrote these praises to Toronto, you'll see they all have something to sell from people thinking that Toronto is the place to be. Usual incentives include: difficulty hiring cheap talent, astroturfing for more VC money, selling a Toronto-tech related product.