The go runtime has been shown to handle millions of goroutines, and there are performant and scalable programs, like Cloudflare's RRDNS that run tens of thousands of goroutines (https://blog.cloudflare.com/quick-and-dirty-annotations-for-...). There's plenty of web software using this model written in Go.

I haven't done UI programming in Go - but in your example, I'd imagine you could simply have an event launch a goroutine - you could do whatever you want in that routine without blocking the main thread and simply pass a message back to the main thread if needed. Managing the number of goroutines isn't something you have to think about in go.

`Task.Factory`, and `Task.Run` still create threads, OS threads, which are different and much, much heavier than goroutines. You'd run out of memory trying to create 1000 OS threads, where as 1000 goroutines are a walk in the park (not just for Go, but for most runtimes using M:N threading).

async/await does have it's advantages over coroutine style concurrency, but I wouldn't count thread count as one of them.