Good, good. Someone who doesn't care enough to support their claims (which fly in the face of established science, no less) expects said claims to be trusted prima facie. As long as we understand each other.
BTW - Less than a minute on google turned up
this study that disagrees with you.
You make a decent point, however, it's not as if some people can magically get sufficient REM sleep in < 5 hours and some people won't get sufficient REM if they don't sleep > 10 hours. REM sleep always follows periods of non-REM sleep (the sleep "cycle"), and a person has to hit enough cycles to get sufficient rest. While that can vary from person person, but it won't vary
that much.