I'm mostly retired now, but I was lucky enough to enter the software world as a designer, then I learned to code. So I could actually roll out a node.js - based app, or a Java-based middle tier, implement a Java Future class if I need to, and even tinker in the DB if I was desperate (I know just enough SQL to be dangerous). Because of that, I was able to debug just about anything, from authentication issues to a gnarly CSS bug.

That's full stack.