> They got rid of the safeties pretty late, when they ripped out their GC, but kept their false promises all over.

This seems like a non-sequitur to me? The presence/absence of a GC is not dispositive with respect to determining "safety", especially when the GC itself involves unsafe code.

Huh? It doesn't follow that forbidding blocking IO is either necessary or sufficient for concurrency safety, at least under any definition of "safety" I can imagine. What do you mean? You mean async-not-blocking-event-loop stuff? That's not the only way to do more than one IO at a time.