I've ditched almost all state in my React apps except state local to the component.
Custom events do all the work for passing information around the application and directing activity.
What do signals give me that events do not?
However you can use signals for local state as well and they work amazingly. Being able to assign a new value to a signal without having to go though a setter is a way cleaner pattern, in my opinion.
The other use cause is for communication between micro frontends. It’s so nice to just be able to import/export a signal and get its reactivity. Before them, I would create a pub/sub pattern and that’s just not as clean.