How would those accounts acquire sats for upvoting? They would have to have their comments upvoted to get some sats first. Overall it's just harder to gamify, I think.

Can't you create accounts with throwaway emails?

Sounds like you are describing a bot net to gain influence twitter-style. I think what makes this different is the need to commit sats, and to have a lightning node per account for the authentication. Raises the cost of sybil attacks, with the idea that it makes them economically infeasible.