Only if where you work and purchase necessities is far from where you live. If you live close or work remote, then it would be easy and convenient to walk.
Well planned communities can be close to car-free, at least for day-to-day activities. The problem is we haven't prioritized being nearly car free, choosing instead of externalize the costs of car culture (pollution that generations will have to deal with, health impacts on some community members today, depletion of fossil fuels and the impact of digging them up, vast swaths of land dedicated to flat tarmac for car storage).
They want to see sights 90 minutes drive away. 3 hours drive away. And be home again that night.
I support "local living without cars as much as possible", but I think cars are here to stay for most of us.
"The cities we live in are hundreds, if not thousands of years old. The idea of that a 15 minute city has any bearing on real life is sadly laughable."
The two sentences don't make sense together. Those old cities were "15 minute" cities by necessity - easy long distance travel wasn't a thing until the industrial revolution. We've since redesigned many of them for car use, and in some cases realized the mistake and redesigned them again (Amsterdam, for example).
There will be various solutions to our energy and pollution problems, and some of the variations will depend on the region the solution is being implemented in. I don't think solar power will be as big in Canada as in, say, the Sahara Desert.