For example some people reach for it for fetching data in routes. It wasn't until recently that routers started to come with built in patterns to do this without effects - example being react routers (it's been a while since I used but remix had this) loaders and tanstack routers beforeload and loaders.

People fetched in an effect because at the time this was the most simple and obvious place to do it unless you were very aware of the other ways to do it, and we didn't have primitives like react query either.

Another example of a non obvious things logging an analytics event when a specific component renders. You could attempt to tie this to the specific update that caused a component to show but that update may be very complex or hidden since your component could show based on a variety of states and require so much more work vs just logging in an effect.

I guess one could argue both of these themselves are syncing operations, syncing your network state and server state for API requests in routes and analytics. But at the same time reacts team told everyone if you're fetching in effects you're doing it wrong without providing the answers.

That to say yes effects are not a very good pattern for many things we use it for and should be avoided, but react as a framework (yes it's basically framework in my opinion, we're well past just. library point) itself does not educate well or have easy to understand built in ways to do these things that are VERY common use cases

And this as someone who writes mostly react.