Anyway I agree with everything that's said in the topic except from the fact that I don't really find that mysterious.
I am pound for pound best squatter and deadlifter in my gym but on the internets I am average. Why? Let me explain that to you. Key is: numbers. There are maybe 100 members at my gym. Most of them are average Joes with no ambition to bo anything, they just don't wanna turn into fat blobs. Some of them are ambitious, but lack my natural talent for squatting. Many of them don't know how to train and obviously don't browse internet boards. I am one of the few that do that. That being said, in the internet there are hundreds of guys like me from every gym on the planet. Those who browse bodybuilding boards are most of the time most dedicated and passionate ones, so level of competition is quite high. Of course some of people here lie or do half squats (especially bodybuilders claiming insane numbers). But I estimate those to be about 30% and even if we take them out it doesn't change much.
Anyway one quick observation: I always go down with my bench once I go off. I am so weak on bench it's hillarious, my personal best is 110 for 4 weighting 73kg. Even though I was never really that consistent bencher becouse I hated the lift I can fucking improve my deadlift by not deadlifting and it never goes down. When I go off my deadlift actually sometimes go up becouse I load on creatine, lol. Same with squats. Drugs never really made me progress faster with squats or deads, it mainly improved my shoulder strength.
I think it pretty much explains why so many bodybuilders bench 200kg easily while struggling with 200kg on half rep squats...