So I've worked places where a user story is the only kind of story and one developer is responsible for every part of the stack for a given story. It didn't work as well as dividing responsibility between front end and back end specialists. I think full stack is a leadership role to figure out the API and integration, but I'm not sure that's even necessary given good communication.

Does it work? Sure.

My experience? I have rarely had a completely healthy team with good leadership and good developers. My experience has not been as good on full stack - it primarily creates different silos so you still don't have interchangeable developers. But I can't say with the right team firing on all cylinders wouldn't succeed.

Team size? Everywhere from 5 to about 20 with full stack being the case at the biggest and smallest. The biggest team was basically segregated by application so each app was siloed to a developer or small group. That was the absolute worst, though I guess the devs were largely happy because there was essentially no code review or supervision.

Quality and team cohesion were so variable I would hesitate to attribute that to full stack devs. Product cohesion was the absolute worst on the larger team of full stack because everyone solved every problem in a unique way and often differently between different apps due to better developer knowledge or different original developer and tech debt. But that was a poorly managed team altogether to be honest. It feels true but all I have is anecdotes.

So overall I'm not convinced it's a good idea, but I'm curious to see the other replies.