that being said: I think people should write the libraries they want and that they use.

If you don't use async? Don't worry about supporting async! Always use async? Don't worry about writing a blocking library!

Either find a co-maintainer that does, or don't worry when someone forks and adds async/blocking, or just writes their own! You can link to each others crates for people that want X, and you can take good ideas back and forth (or even share code where reasonable). You're allowed to say, "no, I don't want that", particularly when you are not being paid for it.

Similarly: don't be an ass if someone does something you don't like! If they write a really good async library but you don't like async and don't want to use their driver, don't! If they wrote it blocking any you want it async? Make the change and offer it up as a PR! If they don't want it, that's okay!