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.