You only have room for a few hundred friends in your life. Sure there might be 500 people who live in 5 minutes walk - but that is too many and so you will learn to take steps to limit the number of people who will accept an open invite.
If you are a Hindu living in a small US city you will find and becomes friends with every other Hindu in the city - there are not very many and you stick together. If you move to a slightly larger small city you will discover that there are too many Hindus and it is hard to make friends with them because their friend groups are already full. (This is a real example from someone I work with, names and exact cities not given for obvious reasons)
I guess my comment wasn’t clear, but I’m saying if on average half the people are not social, then in a city that leaves 250, which as you point out is plenty. In a suburb, because the total population of a block is smaller, the variance in the percentage of anti-social people is going to be much higher, even if averaged across all blocks you still get 50% (or whatever the population average is). If the number drops to 20, for example, my experience is this is less likely to form into a “community.” Twenty is a lot of people but you need more because any given person isn’t available much of the time.
This matches my own experience of living in the suburbs where some streets are way more interconnected than others.
To be clear I’m not claiming this is rigorous social science. Just sharing my intuitions based on experience.
If you are a Hindu living in a small US city you will find and becomes friends with every other Hindu in the city - there are not very many and you stick together. If you move to a slightly larger small city you will discover that there are too many Hindus and it is hard to make friends with them because their friend groups are already full. (This is a real example from someone I work with, names and exact cities not given for obvious reasons)