Effectively, I think the structure of American cities have always been designed fundamentally to decrease togetherness outside of churches and hence today increase loneliness. The basic principle since the puritan arrived has been that an idle people gathered together were a danger. Hence laws against vagrancy and idleness, the non-existence of anything like the promenades of European cities, the prohibition of alcohol and later marijuana and so-forth. The Occupy movement of several years ago, for a further example, was ended merely by enforcing all of the existing against camping, loitering, disorderly conduct and so-forth [1].
Today, rent is so high and homelessness so prevalent that any location that allows people to mill about freely is going entice homeless to sleep and hence will attract repression.
There are locations calling themselves "community centers". They only rent their common rooms for $25/hour or more, an amount that makes it impossible for most informal, average individual to afford.