[moonchrome]

>NO, just no! Async or similar approaches were motivated by super parallel concurrency (classic example is connection handling for a webserver) to have better performance vs the overhead you'd have with os thread primitives (and even there, nowadays, that is just a motivation that is not always true anymore..)

No - that's completely wrong.

Event loops existed prior to them being popularised for IO scaling - they were used in GUI for way longer.

Async is just a way to transpose continuation based programming and the callback hell involved in dealing with event loops.

Writing UI code even in multithreaded code, without async, is a PITA because UI frameworks expect UI state to be updated on the UI thread - so you need to do work on thread X then schedule a callback on UI thread and update UI state. With async you just fire off a task, await with scheduler on the UI thread and you have linear code flow.