Earlier quoted context omitted.
> Eventually you will get to a point on that exercise where your concentric pull can put up vastly more weight than you can safely lower to the ground in a slow manner. I'm not particularly qualified to speak on this, but this does not match my experience. I can deadlift 455 lb with great difficulty, but I can lower 455 lb to the ground fairly easily. And I don't see any physiological reason why this would be true—if…
Gravity acts over time, if you are slowly lowering it you could be expriencing the same force practically as on the way up. The reason you don't do it for powerlifting is because you're more likely to injure yourself after a max effort lift (like a one rep max lift in competition). Since you exerted maximally on the way up and may struggle controlling it on the way down it while exhausted. All the other compound lift…
If you’re hellbent on doing long eccentrics on your low back, do it on back extensions with light weights. I used to do them. I always regretted it the next day.