I was in the gym at the local YMCA on machines for 4 years, from 9 to 13, at which point I quit because I had a falling out with my dad.
After that I just rode a BMX bike and did push ups and pull ups for 4 years, and I deadlifted 295 lbs my first day when I was 17. I was 160 lbs, at 6'1". Same height I am today. I'm 65-ish lbs heavier now, ~90% of which is muscle.
I also carried around dead trees for fun. I was an odd kid.
Some people are just freaks. They are immensely strong, and always will be. They could just do push ups and pull ups and run around, and go deadlift 2-3x their bodyweight no problem.
Others are fairly well-trained overall, and will start off with fairly impressive lifts as a result. They have average gifts physically, and with training can be pretty impressive.
There are also plenty of people who go through similar training and are not particularly impressive, because they are pretty poor responders to exercise and don't adapt at the same rate... they are simply not physically gifted to even an average degree.
They're not going to tell the same stories that you hear in this thread.
Most of us don't talk about how much inherent variation there is in the human race, including physical capacity, but it's there.
The idea that everyone can become immensely strong with hard work and effort is, to some degree, a fairy tale for some people.
There are a lot of people who would have to work a lot longer than I have to achieve half of what I can do even with this busted body I have, and there are others who took 2 years to build strength I needed 5 years to build. Some of them have strength I will never achieve, no matter how hard I try.
That's reality.
Having said all that, any exercise that really works your whole body well, as a sort of GPP routine, will by its very nature lead to you doing pretty decent things in almost anything you try. You may not be the best, and you may not even be average, but you'll still be way stronger than you would have been otherwise.
Sometimes you have to focus on what you CAN do, not on what other people can do (or have done) but you cannot.