Every site that can be random-user-edited or allow comments are infested with shills, grifters, astroturfers, scammers, spammers, propagandists within minutes. This only increases as the site gains popularity. What each site turns into depends on how it was engineered, how it is moderated and actively managed it is. To me personally I think that Wikipedia may have been purpose designed to let this happen or it would have stopped happening a long time ago. I am certain everyone here could each think of a dozen ways to minimize this behavior.

Just as one example if it were up to me the edited version invisible until a panel of moderators gives the edit a +1. If a sub-set of moderators give it a +2 (override) everyone can see who did that. Moderators would have to show real names and their country of origin and current country of residence. A watchdog group must be able to vote out moderators. If users try to overwhelm the moderators then they get perma-banned. I would probably not allow edits from wireless devices. Edits must be treated like changes to the Linux kernel and I want the original abrasive version of Linus back for this but that's just my personal preference.