You forgot that they do suited squats, the mechanics are completely different. Training for maximal raw strength will hit quads hard, it's impossible not to. The westside guys stand ridiculously wide and sit back, you "can't" squat like that raw. And you will not hit any kind of below parallel like that.
Exactly. It's nice to read commentary from folks who know something about that which they speak.
"Sitting back" is a great thought, and applicable, to some degree, for every squatter, but for the non-suited, non-mono-lifting, non-super-wide-stance trainer, that application will be much less pronounced.
As said above, a very strong squatter, one who does the movement raw (or without a suit, at least), will almost always have impressive quad/low-quad development.
As usual, Louie speaks only in terms only 100 percent applicable to his club and how he and his athletes perform exercises.
(Also make note that he believes drug-free lifting is a waste of time. Oh brother.)
For all he and his club have done for powerlifting, they have have also wounded the sport in equal measure.