I'll add (3) the only reason IRC isn't equally abused is because it's so bad that it can't attract enough people to justify any kind of ad-based (or otherwise)

I'll add (3) the only reason IRC isn't equally abused is because it's so bad that it can't attract enough people to justify any kind of ad-based (or otherwise) monetization model. IRC is the opposite of being a victim of one's own success. EDIT: I should note that beyond being more usable than IRC, I have precious little good to say about Twitter.