My understanding is that any participant action requires proof-of-work. Social networks like Secure Scuttlebutt prevents this type of attack by syncing only da

My understanding is that any participant action requires proof-of-work. Social networks like Secure Scuttlebutt prevents this type of attack by syncing only data within social trust circles. So spammers and bots can vote up each other all they want, but their actions will not be visible outside of their little island unless someone explicitly "friends" one of them. Aether, being a global view of unpartitioned data, has a more difficult time tackling this type of attack, and its proof-of-work minting of user actions seem like a reasonable approach.