Oh dear. If misreading perlthrtut is the extent of your knowledge, you really shouldn't even reach mental conclusions on the subject, never mind offer them up in writing as proof of your own ignorance.

How could what you are saying possibly be true, when I and 100s of others run ithreads on Windows everyday. Windows doesn't have a fork api.

Here, check for yourself. You just might learn something useful. (Like the fact that on Windows Perls, ithreads are used to emulate fork--not the other way around.)

(Hint: that's not a question, the answer is obviously that it isn't, and couldn't possibly be, true.)

You (and Marc Lehmann) need to understand the difference between a) a program model; b) the actual implementation that underlies that model.

Coro isn't "threading". It's good, old-fashioned, cooperative coroutines--just like Windows 3.0; with all the same problems--and nothing more.