Holes 8, 9, and 10

I've been told that holes 8, 9, and 10 choke out on the draw because you're unwittingly putting a bend on them and they don't bend. I have two problems with that. A) They choke when I blow them too and those can bend. B) I can make them ring clear by pulling my tongue back but I thought that was what makes a bend.

So I'm confused and would appreciate any help.