It seems like you're taking this from a perspective of "Pthreads in C++ vs Coroutines in Go", which is correct in some respects, but different from how I was taking the discussion.

I guess I was taking it from a perspective of "pthreads in C++ vs Go-like coroutines reimplemented in C++", which would be pthreads vs C++20 coroutines. (Or really: it seems like this "Loom" discussion is more of a Java thing but probably a close analog to the PThreads in C++ vs C++20 Coroutines)

I agree with you that that the garbage collector overhead is a big deal in practice. But its an aspect of the discussion I was purposefully avoiding. But I'm also not the person you responded to.