"Oh...THAT kind of cycle"
It's true; we've come full circle and now, here I am, telling you that you need to build your UPPER body. And "build" is the right word here. You're not going to cut it with your 15 reps of bench one day and your 15 reps of press another and maybe some chins and rows here and there. You don't get to build your upper body the way you build your lower; it takes some serious hardcore volume, effort, and godforbid bodybuilding to see the progress you want to see.
It's easy to get tricked into thinking you're hardcore simply by training your lower body at all. Yes, it's true; a lot of folks simply don't do ANY lower body training, so you're ahead of the curve that way. And yes; a heavy, high rep set of squats or deads absolutely sucks. However, that's the thing; just 1 big ass heavy, hardcore, miserable set of squats or deads is enough to really get the whole lower body growing like a weed. 20 rep squats was great evidence of this, and there have been several successful training programs with a minimal amount of sets dedicated toward the squat and deadlift. Since you can move so much weight with these movements, volume becomes easy to accumulate in short order, and you can get your work done quick, even if it's brutal and terrible.
Never have so few sets created so much muscle...and vomit
The upper body doesn't enjoy this luxury. In most cases, the weights you can use for your upper body are paltry compared to your lower body, which means that one big ass set most likely won't do the trick for growth. You're going to need to hammer your upper body with work to get it to grow. And guess what; your upper body has a back side AND a front side. When you hit a heavy set of squats, you get to train the back and the front of the legs all at once, but no dice for the bench or press. Yes, I know some nerd right now is going to go to exrx and tell me that the bench relies heavily on the back, but go do me a favor; go do nothing but bench for 10 years, then take a photo of your rear lat spread. Yeah; you need to train both.
So we already understand that we need to spend more time on the upper body simply because we can't hit it all at once like we can with squats, and that we also have to spend more time trying to accumulate volume. The other thing to factor in; the upper body lifts have to rely on tiny little muscles to get the job done which; surprise, you can't lift ANY weight with. Once again, you look at a set of squats or deads and you're using some BIG muscles to get the job done. If your quads are weak and need bringing up, you hop on the leg press and move 1000lbs, or you go hammer out some heavy front squats or backwards sled drags or something heavy and aggressive. Guess what you get to do if your medial delts are holding you back? Lateral raises. And unless you're Branch Warren, it's gonna be with some pink dumbbells to really get the pump. Weak biceps? Hope you like some curls, and unless you're Ct Fletcher of Magnus Samuelson, it ain't gonna be heavy.
Keep in mind; most people do this with far fewer plates on the dumbbell...and less muscle...but sometimes equal amounts of swearing
And now we've arrived at WHY there are suddenly all these Captain Squats running around with zero upper body growth and silly high squat numbers; because it's no FUN building your upper body. Not the way it is to chase squat and deadlift numbers. It's awesome seeing the plates get slapped onto the bar, 1 after the other, and grinding away a few heavy reps or 1 big drop set and seeing growth week in and week out. It's not so awesome spending weeks and months just to add 5lbs to your press, and knowing that you get the super exciting joy of chasing your press workout with 3 rounds of the shoulder shocker with 15lb dumbbells. But, get this, it's the people who just do the work that get the results. All you kids trying to get jacked with 15 reps a day are spinning your wheels; it's those idiots you're mocking in the gym spending an hour on shoulders who are finally going to get somewhere.
THIS is why you see so many guys with jacked upper bodies with small legs; not because it's easier than building a big and strong lower body, but because it's more "fun". Meatheads like to lift weights, and you can spend way more time lifting weights for your upper body than you can for the lower. You go to the gym 4 days a week for 2 hours at a time and you can get a jacked upper body. You do that for the lower body and you end up getting rhabdomyolysis. Or you're running Smolov. Who did Smolov train again? Anyway, I digress.
Looks like it worked great for this guy!
Take a page from the meatheads you've been mocking, because clearly it's been working for them and FAILING for you. You don't have to live with envy; talking about how you're clearly the superior lifter because you squat 315 for reps, even if your upper body looks like it belongs to a 9 year old. You can be big and strong EVERYWHERE. Spend some time grinding away on those lifts you make fun of people for doing. Do your curls, raises, lat pulldowns, pushdowns. You could also get crazy with some kelso shrugs, and actually start doing a good amount of chins and rows (shoot for 50-100 reps a workout to start), and just get big, jacked and wide.
A little muscle never hurt anyone. Go build some.