I think the trouble is that due to changing how reactivity works in Vue3, really it’s a completely new framework that just looks quite like Vue2. I don't think they could have made the changes in a phased way, it’s a kind of all or nothing situation.

This time last year I helped with adding Vue3 support to the TipTap editor and went headfirst into Vue3s internals. It’s a completely different machine.

Vue3s changes to its reactivity system is like Python 3s change to make strings Unicode.