2TB model: 5000TBW
256GB model: 2000TBW
That means that, at the worst known rate that David had (150TB in 2 months), a 256GB drive would reach lifetime writes in ~2 years. That's still way too fast, so this is still something Apple needs to adjust if it is happening to people (and given what he told me about the write rates he was seeing while using and switching apps, it really does seem like a bug, not normal app swapping).
FWIW, the "app nap" thing is what iOS does, but macOS can't do that because Mac apps aren't really designed that way. macOS just does traditional swap plus compression, as far as I know.