Sagas are a great power tool, but most Redux apps don't need them. That's why we opted to include thunks out of the box as part of our official Redux Toolkit package:
https://blog.isquaredsoftware.com/2020/02/blogged-answers-wh...
(You can still customize the middleware when using RTK to set up your store, same as always, so if you want to use sagas you still can.)
That said, there's a lot of things thunks _can't_ do, and for those use cases it makes sense to use sagas or observables.
So it may help to think of JSX as using a functional subset of Javascript. It's not, and that veil gets pierced pretty often, but the better you contain it, the more you can effectively use both Javascript and HTML together as part of a single concern.
Using Redux with sagas even further separates out the most side-effecty parts of it, though sagas are really heavyweight and I'm still not certain if I think they're worth it.