My cynical take is that an unholy pact was formed between FE devs and UX designers:
By adding in "design" and "user experience" you essentially reduce features, complexity and general "dev time" of every single user-screen or page or component. They're no longer cram-packed with oodles of features, toggles, buttons, menus, etc. Most pages are glorified lists of things, with maybe a menu on each item if you are lucky. Devs dev less, have less bugs, just use FE-library of the day and go home happy because they made a CRUD screen essentially.
Meanwhile, UX designers get to play around and constantly fiddle with design because let's all be honest, nothing will ever be truly good and in a perfect "user experience" space because complexity and functionality are never what the user is happy about having, until they need it.