Well... yes and no. I agree that's how things should be. But I have seen perfectly good backend devs flummoxed by react and front-end devs completely lost as

Well... yes and no. I agree that's how things should be. But I have seen perfectly good backend devs flummoxed by react and front-end devs completely lost as to the subtleties of various back end components. Our organization has a few "DB subject matter experts" who have been optimizing relational db's for decades. We don't ask them to build web pages. Specialization is a thing. Saying "everyone can do everything" is sort of like "with enough eyes, all bugs are shallow." There's some truth to it, but you quickly find corner cases which disprove the assertion is universal.