This is a fair criticism, but except for the inevitable bugs/regressions introduced by the rewrite, the devs aren't directly affecting the UX (making it worse).

This is a fair criticism, but except for the inevitable bugs/regressions introduced by the rewrite, the devs aren't directly affecting the UX (making it worse). More importantly, they're not deliberately sabotaging functionality -- the article's Economist app example -- in their quest for the current hotness. This is why "it's the PMs" is a refrain -- because the changes they make are very tangible in the end product.