nah, we partied plenty when we rented and not knowing someone for long is not a reason not to hang out. What has been eroded is the habit of hanging out because there's no easily accessible third spaces. I'll give you an example: when I lived in Spain I would just walk in the corner bar for a quick beer or a coffee or something to eat, I would very likely run into a neighbor and would chat. The chat would lead to "hey let's do something". In the USA it's almost always the case that people need to make plan, the lack of spontaneity kills most plans.