> I took that example from the current official Vue 3 docs:

Yes, that API also exists as compatibility with the Options API, but this is what you should use:

https://vuejs.org/guide/typescript/composition-api.html#typi...

> So 2 years into Vue 3. Has anything changed?

Yes, e.g. templates are type-checked now. If you have specific things that aren't supposed to work, please list them.

> The real dealbreaker is still the reactivity system which leads to spaghetti very quickly.

I've had much better experiences with Vue than with React in this regard.