It needs to be coupled with effective and merciless moderation towards that behavior. When your single spam post costs you $10 and it was deleted and you were

It needs to be coupled with effective and merciless moderation towards that behavior. When your single spam post costs you $10 and it was deleted and you were permabanned within a few minutes, the only thing it's effective at doing is draining your wallet. That's not so say you don't see that behavior on SA, but it's pretty unnoticable unless you go looking for it (and it keeps the lights on there). twitter has created the problem for themselves of few moderators relative to users, allowing spam, and giving the benefit of the doubt to suspected bots