I did blocking design using Duktape for my runtime Linux distro reinstallation tool and some other projects. It works fine and it's easier than implementing async aware bindings.
I wouldn't implement it for the HTTP server/backend use case, because I find the blocking/share nothing architecture of PHP limiting.
The point is the language doesn't prevent this kind of architecture.
As much as I'd like to see it, your JS without an event loop is a purely theoretical construct so far.