ok it's possible to squat over 600lbs naturally now.....
1) You already state that you have shitty genetics....so does some bias come from that?
2) Have you EVER trained like a powerlifter???
3) My best squat was 500lbs and deadlift was 565. I never trained like a powerlifter. I had the high bar/bodybuilder placement for squats and the deadlift was sumo stance.
You talk about doing 5*5....but how much gain have you actually made on it? Personally I didnt find it useful/help me in any way. Here is my take on it. This is BY FAR from a melt down.
Most guys will look at a routine that is powerlifting based (russian squat, smolov, etc) and say..yeah I want to squat heavy...blah blah blah. They do it and then they look around at their buddies on bench day and see that they are going all out and shit. Unfortunately your routine doesnt call for benching that day...but you decide to do chest with your buddies because 'you could always move your workout days around'. So, then this happens a lot....you turn around and say 'that routine didnt work'.
I did the old MuscleMedia 2000 50lbs on your bench and it was great. Same with the russian squat routine...I didnt care about other lifts as I was only focused on doing my routine.