On university campus and in companies it's a natural occurence. You can have good or bad company culture but there will definitely be a company culture - which seems to be the problem at places like this. There simply isn't a culture.
The size is definitely part of the problem, 500 is way too many. On the other hand I also know people who share house with four other people but have no relation with them.
There was/is a code of conduct and lots of events at The Collective that tries to bond people together. Some people made friends and had their own little group they hung out with but it seemed like most went to a few events and then stopped going.
I might be pessimistic but I think it all comes down to a shared purpose - which you can't enforce unless people work, study or are obsessed with the same religion/politics/whatever.
And yes - it's definitely not designed by people who would eer live there.