> which in turn let the others do less and less.

Force the others to do less and less. I’ve seen this a million times, you have one dev going absolutely buck wild building a cathedral of abstractions that only they can understand. The rest of the devs struggle to implement basic features because, and I can’t overstate this enough because it’s true every time the code is a horribly written tightly coupled shoddily architected ball of chewing gum of twine spooky action at a distance with no isolation between components (usually because “DRY”) which is impossible to reason about unless you wrote it.

That dev becomes insanely productive in that codebase, the hero of to all managers, and everyone grinds to a halt gets demotivated because they can’t tackle anything ambitious.