[AlexandrB]

> From an online discussion point of view I don't think it holds merit at all. If I run a football board and have a rule that says "no basketball talk" that's my prerogative.

I think this is absolutely true. But things get murky when you're talking about sites like Facebook that are a primary means of communication for a significant part of the world's population. Because there's no "public space" online, large social networks become the de facto public space. But because they're not truly public they can do things like censor speech that would normally be allowed in the town square.