You have no control over concurrency/scheduling, have to manage scoping, error handling, etc. TPL/Threads add to much low level noise to the logic.

Like you could easily blow up the thread pool depending on what you are doing, where a channel based implementation would just deal with spillover and not affect the other threads. You can easily capture scoped services that are disposed by the time the thread executes - but you never catch it in dev because you get executed immediately and request takes long enough, etc.

Spawning threads will work but I can see the use in a small abstraction like this lib for sure. Not sure I would use a lib for this - would probably hand roll something since I don't like adding unvetted external deps by default.