And yet so often UX Writing is distained as an unecessary job that can be handled by designers or PMs instead of recognising the verbs and nouns of your product are its fundamental architecture to users. And that's before you get to voice & tone.
The question can easily be shifted to ask, why only devs doing development, couldn't PMs and designers do it too? Well, yes they can. At least parts of it. HTML, CSS, definitely, maybe some basic JS too. Could devs do PM work, I think so, at least little bits!