In my experience that the frontend/backend separation was something that came out of developers who only wanted (or only knew how) to work on specific areas of the system and got business to adapt to that. Business and non-technical people eventually accepted, but many still long for the days of full-stack devs.

And I'm with business people here: coordination between multiple devs is definitely an overhead that impacts businesses and heavily limits possibilities of experimenting and iterating with ideas.

The separation is also often a kick the teeth of Agile ("we gotta do the backend before frontend starts") and performance ("just call those 5 endpoints N times, we don't have time to make an aggregated endpoint, should have told us before"). You can still have specialists for micro-optimisations and fine-tuning that SQL query, but the initial implementation phase really suffers from the separation.

There's also lots of "prejudice" and pedantry around the term "full-stack", and that's almost always from less experienced developers or students (which is why you don't see it here in HN but see a lot on Reddit), but that's another discussion.

It's even worse with developers who had some design training, IME. "Oh you say you had design training but I'm 100% sure you're absolute garbage in either that or in database modelling. Or perhaps in both!"