Toronto, and a number of other big Canadian metros, hit a tipping point quite a while ago where it became clear that they couldn't keep sprawling out indefinitely. Canadian urban planning did a complete 180 a few decades ago. Almost universally across Canada, policies encourage TOD (Transit Oriented Development) to decrease congestion, shorten commute times, decrease gas consumption, lessen the amount of gas wasted by cars (often stuck in gridlock), improve air quality, and to create nodes dense enough to support public transit options like subways.
Rather than have absolutely everyone traveling from suburbia to the downtown for employment, shopping, entertainment, and higher education urban planning policies support the development of dense clusters scattered throughout the metropolitan area.. These clusters act as mini-downtowns and negate the need to travel to the big downtown.
The Greater Golden Horseshoe has 25 nodes at various stages of development