It just doesnt generally work how I would expect it to work until you learn the details of how to make it work how you expect. Especially as you get into RX it gets really confusing about which execution context you should be on. And execution contexts in mobile land are pretty convoluted to setup IMO.

So yes "async" is easy, but "multithreaded/parallel" is a lot more error prone and explicit.

EDIT: I should also note I havent been in the space for a few years so Im not fully current on how it looks today