`spawn_blocking` is a single function and it is not complicated, it shouldn't be too hard for other runtimes to do the same. The end application does have to c

`spawn_blocking` is a single function and it is not complicated, it shouldn't be too hard for other runtimes to do the same. The end application does have to choose a runtime anyway and will have to stick with it because this area isn't standardized yet. This problem mostly affects the part of the ecosystem that wants to put complicated concurrency logic into libraries.