Or is it sufficient to us the build in reactivity system of Vue or the other frontend frameworks like in SolidJS.
I think it is the same question like using Axios or fetch?
You don't have to axios any more in times of the fetch API and it makes your source easier to understand.
The argument to use them get killed with the next one coming up from nowhere. So why using them at all and how often do you really need them to share a state between to components.
Less is more.
What do you think?