The 15 minute city is a great idea, and one that comes from 'New Urbanism' of the 1980s. Nothing new here. Its crazy that the UK is having such a strong reaction to it.
But unfortunately in many cases walkable cities has been implemented badly, removing cars and buses, but not replacing them with viable forms of transportation. This can create 'dead zones' of nonfunctional space in cities. Another problem is how do you bring people from the suburbs into the city to work, shop and play, without cars and parking?
We definitely need to rethink the post-WWII industrial city, but we also need to listen to people's lived experience. We need to make cities walkable by providing more amenities, not by taking away their transportation options.