Hybrid languages are sub-optimal in a lot of ways. One of the joys of functional programming are the guarantees that imperative languages can't offer (primarily immutability).
Sure, technically a single computer's local RAM is being managed with strict guidelines, but that correlates less and less to overall application state and behavior these days.
The problem is that nobody made an usable FRP system yet. It's not obvious why it's so hard, and everything feels like it should be easy. But everybody just keep failing.
Knowing that a small collection of functions is not referentially transparent is better than having to deal with any part of the program potentially changing your state.
The real world is messy and stateful.