This is likely to be especially problematic because in any creative endeavor there tends to be a lot of variability, so if there is a "star" they'll likely start to resent "carrying" the others, and anyone who is perceived as posting "filler" content will probably have some resentment that their contributions aren't appreciated.

Yeah, this is true, but the assumption that's baked in there is that the initiative will succeed - at least to some extent. There won't be a "star" carrying anyone if the whole initiative fails. How many rock bands have we seen break up for the exact same reason? Some last, others split apart. I also envision some authors being "voted off the island" by other team members.

As time goes on, I would imagine that teams would come up with more sophisticated reward-sharing strategies and other governance mechanisms to try to mitigate these sorts of challenges, but in the end technology can't really be expected to fully solve the human problems that exist in all creative endeavors.

Having to manually set and monitor the beneficiary payouts will make it constantly salient for the people participating.

Also true, and over time I would expect interfaces to evolve that have the right beneficiaries set by default. For that reason, and also just because setting beneficiaries by hand is a pain in the a$$ and easy to forget. This particular challenge is fairly easy to address with technology.