Exactly. I dont know any instructors who advocated straightening the right knee on the backswing. How are you supposed to get onto your left side if your right leg is straight and wont allow you to push off and shift your weight to the left side?
Also, using tour pros' swings as a model is never a good thing because those guys are freaks of nature and almost none of them have a mechanically perfect swing in the first place.
I actually used to straighten my right leg on the backswing and since focusing on keeping some flex in that leg Ive gotten more consistency, straighter shots and more distance. I used to hit a big ole block shot because I wasnt able to get onto my left side.
If straightening the right leg works for the OP and for others, thats cool but it didnt work for me.
Did you watch the videos and read the thread?
"Straighten" = decrease flex, not "lock out dead straight." Virtually every golfer straightens (decreases the flex) of the rear knee in the backswing. It allows the hips to turn on an inclined plane (or to turn at all, really).
And it's easy to get to your left side even if you happen to completely straighten the right knee during the backswing.
"Keeping some flex" is not the opposite of "straightening." It's the opposite of "locking out" or "completely straightening".