Recently, I am working on a project that uses Threading (in Python) and so far have had zero issues with that. Neither did I have any issues before, when using multiprocessing.

What I did have issues with though, was async. For example pytest's async thingy is buggy for years with no fix in sight, so in one project I had to switch to manually making an event loop in that those tests.

But isn't the whole purpose of async, that it enabled concurrency, not parallelism, without the weight of a thread? I agree that in most cases it is not necessary to go there, but I can imagine systems with not so many resources, that benefit from such an approach when they do lots of io.