I have squatted for 28 years or so. I can count on my hands how many running/lifting/jumping sessions I missed in first 10 years on one hand.
I have been around lifting my entire life, personally coached probably 1000 people. Done seminars. Written books. Coached at college with "high end" athletes, coached regular middle-age people, coached young kids.
I'm saying it doesn't matter. Squat with the bar where you do best and you'll be fine. When you begin lifting, a person needs guidelines to follow, and I think Mark is the BEST person I've ever seen in regards to this. However, at some point, you will have to make your own decisions. And when you reach that point, you will realize that it doesn't matter.
I hope this is very clear.