All squatting has ever done for me is injure my back
I have not gone heavy either, I popped a disc warming up with 2 plates.
As we grow from childhood are bodies start to change and we lose the flexibility to squat correctly (look at toddlers squatting, their form is perfect) we simply cant squat down without putting wexcess strain on the low back.
Hamstrings lose their flexibility which also increases the risk of inujy when squatting
Im not saying people should never squat down, but putting a weight across the back of your neck and doing it just doesnt make sense.
We don't lose the flexibility just by aging. We lose that ability due to the activities (or lack there of) we are involved with. For example, a sit down job will fuck with your low back and mobility incredibly.
Your disc was ready to go way before that two plate squat. Did you ever have low back pain/stiffness prior to that? Not just the 8 out of 10 type....I am even referring to the low grade "oh, its just stiff" type. If you did, and just ignored it saying "it's not that bad, it will go away"...then that is how it started. I tore my right medial meniscus just warming up with a smith squat with ONE plate on each side. That shit was wearing down way way before that.
I will ask you this...how long did / do you take warming up for a leg session. Most people will do some bike for 5 mins, maybe some half ass stretches, then its load the fucking bar, do some reps, load the bar, do some reps, complain about being stiff, then load more, the squat feels a little better, then load more...etc.
Also, how much POST workout mobility do you do? I would wager that very very few people do things after their workouts. I gather that you weren't being literal, but if someone has the bar on their neck, that bar is way way too high.
Repetitive wear and tear on joints, tendons, ligaments without proper recovery and attention is what causes problems. Look up the cumulative injury cycle. The amount of times I see people talk about how their shoulder or elbow or whatever other joint hurts and won't heal, yet will refuse to take some time and address it is super high. The mentality that stopping for a brief time will cause a massive loss in size is ludicrous.