> Not all code written benefits from async nor even requires it. Running single threaded, sync programs is totally valid.

Maybe, but is it useful to have sync options?

You can still write single threaded programs

I mean single threaded + sync.

Sync options are useful. If everything is on the net probably less so. But if you have a couple of 1ms io ops that you want to get done asap, it's better to get them done asap.