I think you’re missing a detail here, which is that before streaming was a thing writers would make significant amounts of their money by getting a show syndicated on a network, that was the whole deal. Streaming is being treated differently, effectively resulting in then receiving a very large pay cut because even if they make a successful show the payout doesn’t come.
And it’s true they could structure things so that they don’t receive a secondary payout, but their base salary was negotiated with that later payout in mind. You and I don’t receive secondary payouts for our work, but our salary is also adjusted to recognize that.
It seems likely biased as well unfortunately if they let teams decide on their own what to use. I would wager that teams who on their own switched to Rust are probably teams that were already productive.