Except Erlang (and nowadays Elixir as well) has that for 30+ years already and it's done much better -- one green thread per request, and you can have 200,000+ of them at the same time on some fairly modest hosts, without any of them stealing run time from the others (as much as the hardware allows, of course).
PHP's "prescient" model demanded one OS process per request which is frankly absurd and I don't get how anyone views PHP in serious light because of this single fact alone.
