I don't think the scarcity of options is due to any shortage of potential communities on the internet--there's a perpetual scarcity of extant communities due to

I don't think the scarcity of options is due to any shortage of potential communities on the internet--there's a perpetual scarcity of extant communities due to naturally-monopolizing network effects. If Facebook weren't the place, it would be somewhere else. Any old forum would do if it were where the people are.