If such a system is implemented properly, moderation can be done by a third party service on top of the platform. This would be strictly better than the current model, since every specific user could pick a service that best matches their opinion on what does and doesn't constitute spam and other undesirable content.

Better yet, something like Aether, where everybody can moderate for their own feed, and any user can designate any other user or group of users as their moderators to get a curated feed with no effort of their own.