I used "async" long before Node too. It's one of the reasons I knew to stay away from Node.

"ad-hoc implementation of async"

I think you're confusing the problem with the solution. I solve this sort of thing in Go all the time. This is literally what I was doing yesterday. It's fine in that context. You had to reach for async because it was the only option in your context, not because it was the best choice. Async as it is conceived of today was a hack for dynamic scripting languages that basically had no other option. They "won" there because the environments simply couldn't support any other solution, not because they outcompeted anything.