Obviously. My point is that spawning 10_000 "processes" (green threads / fibers, really) on the Erlang BEAM VM is almost not noticeable at all f.ex. in web server mode. Everything just gets a tiny little bit laggier but chugs along nicely. Same goes for Golang's goroutines, though not exactly to the same extent (the runtime does not tolerate as huge a number as easily as Erlang's runtime).
Whereas spawning native OS threads (not sure about the 10k number, could be even more with the good hardware these days) and having them all do stuff is gonna lag a whole lot more due to context switches.
So you know, apples to apples, but some apples are much better than others.
Of course, if they're doing real work they'll be using CPU time, but that's true of any scheme you might pick.