If async were a first class citizen, then it might be the default. Maybe that's an oversight that has to be rectified. It is true that as soon as I start writing a GUI application, async has to become involved. And maybe it would be good to take advantage of async calls to sleep or when opening files and sockets.
As I understand it, the benefits are that it’s a much smaller dependency and (as the article mentions) unlike tokio you don’t always need things to be ’static or even Send, depending on your scenario.
This article talks more about the benefits of LocalExecutor.