1) I don't think it actually uses async/await as it explicitly targets ES3. It's probably just using callbacks or something.
2) Parallelism isn't guaranteed by goroutines anyways, and this is targeted towards building new apps more than it is reusing existing Go code, so it shouldn't really be that much of an issue. Most web apps/SPAs have no need for parallelism.
1) It does not really matter that you think because the author said the following:
"Actually to my surprise, goroutines and channels can be modeled quite well in Javascript! Right now the compiler uses async/await but for 1.0, I think it's possible to compile it down to ES3."
2) Parallelism isn't guaranteed by goroutines anyways, and this is targeted towards building new apps more than it is reusing existing Go code, so it shouldn't really be that much of an issue. Most web apps/SPAs have no need for parallelism.