They need to be really small for that to work, and what's happening is that only 1M+ or even 5M+ population areas are in demand.
A home to 5M people isn't likely going to be very walkable.
A home to 5M people isn't likely going to be very walkable.
Also, if you have a bicycle and decent bike network you can traverse an entire major city in 45 - 60 minutes. The problem is that most new cities are virtually nothing but asphalt and empty land in order to accommodate cars. I am sometimes called weird for saying this - but seriously - look at pictures taken at elevation and a modern "city" looks very sparse indeed.
That's not true. One solution is the '10 Minute City/Neighborhood' and its guide to decision-making.