Angular 2+ is almost six years old at this point too, and the devs who knew v1 still could use it perfectly. And people did successfully migrate back then. And

Angular 2+ is almost six years old at this point too, and the devs who knew v1 still could use it perfectly. And people did successfully migrate back then. And for real: this is "a framework that got a breaking change between major versions". If that’s the worst example we have, I would say the JS ecosystem is doing jolly fine! I've had worst breaking changes in backend frameworks, to be honest. About the other two: like you said, both React and Vue can still run old code, almost unmodified. The track record of those two is way better than most backend frameworks, by miles. It’s not even a fair fight. Sure there's new concepts, but it's not arbitrary stuff or old patterns, it's legitimate stuff that makes writing UIs better. But the old ways are still there too.