I don't mean to minimize the effort of FE as I agree it is under-appreciated. But if the BE folks don't work closely with PMs and designers then you're already fucked and no amount of FE lipstick will make up for it.
Of course many FE engineers have the chops to solve for these things, as well as PMs and designers with technical background, deep domain expertise, and other qualifications that can make up for these gaps. I came up professionally in the early web days and building startups where it was normal to wear many hats, so it's more about skillsets than rigid titles and role definitions. I've just seen a very common gap that a lot of ostensibly professional proddev folks, even at top companies, have borderline magical thinking about the deeper layers of the product stack.