I'm a glutton, so I'm going to try explaining something that (probably) won't make much sense.
this something = torque
(I said torque, not twerk.)
Torque is lethal.
Torque is why a longer wrench makes it easier to unscrew a nut from a bolt.
Look at an exercise like, say, the dumbbell lateral raise. You can't use a very heavy dumbbell for the lateral raise because of torque.
Even though the dumbbell lateral raise is a challenging exercise, the overall load for the shoulders is (gravity) + (weight of the arm) + (ten pounds).
(Assuming ten pounds is a difficult weight for, say, ten repetitions.)
And now bring those dumbbells in closer to your body and press them overhead. You're using similar structures (shoulders, upper back), but the overhead press is OVER 9000 times easier.
So if you wanted to make ten reps a challenge on overhead presses, you need to pick up, say, thirty pound dumbbells.
Forget EFFORT for a second and look purely at these two exercises from a load standpoint.
With the same load, one exercise (overhead press) is a lot easier, meaning you can use more weight, meaning you can expose your body to a greater load.
You'd have to do honest lateral raises with 30 pounds in each hand (not going to happen in this example) to match the overhead press load.
Because of torque, most exercises that allow the most exploitation of gravity+ (and load) are ones that have little torque, which tend to be movements where you
move against gravity itself
in a relatively straightish line
keeping the load closeish to your center of gravity to minimize torque
like the back squat. The bar is on your upper back, meaning you're adding weight to your torso. As you move your hips down and up, the bar travels in a relatively straight line.
Think of the bench press. The bar is in your hands, meaning you're adding weight to your arms. As you move the bar towards your chest and back to the ceiling, the bar travels in a relatively straight line.
Think of the weighted chin-up. You add weight around your waist, meaning you make your lower body heavier. You pull towards the bar in a relatively straight line.
And, usually, with all of the exercises listed above (and their similar variants), the more weight you have on the bar (or attached to your body) the more linear the lift will be.
So when you zoom out and look at the meat and potato exercises often recommended as good muscle builders, most of them are (a) closed chain (b) vertical path exercises. Because these types of exercises allow for the most exposure to gravity+.