Yea I'm 6'2 and 215lbs. You don't realize how much strength you have in your legs. Realistically, the first few months of your training is teaching your brain which neurons to fire to get a smooth movement. Plus, I've been training for 9 months now pretty solid this go around. I used to train years ago when I was pretty young (18ish).
No, it does not take some serious strength to squat over 400 for someone my size. For someone your size it won't happen, but I've got nearly 100lbs on you (most of which is lean body mass anyway). For someone my size, serious strength is like 600 or 700lbs. Your legs are big fucking muscles and can move some serious weight if required. Anybody with any experience doing big lifts can tell you that.
And my bench is very imbalanced; unfortunately I don't have a spotter and doing a 5 x 5 isn't good for me with a heavy load. I progress pretty linearly though. I know guys that squat/dead over 400 that took years to hit two plates a side at the gym (225lbs). My chest is definitely my achilles tendon. It sucks.