RxJS: The Great and Terrible. Describing Complex Stack-independent Asynchronous Logic

We deal with asynchronous logic every day: reacting to user clicks, sending a request to the server and waiting for a response. Frameworks reactively display new data that we've just changed. It seems as if asynchronous code is not a problem, until we have to write complex dynamic logic with many intermediate states. What if we just write this particular logic in RxJS? Nah, that's crazy. Or is it?