I could break this down all day long but lets make this very simple shall we...
1) First of all lets take every guy with shitty genetics for musclebuilding/bodybuilding that has great genetics for absolute strength out of the equation because thats what people build their arguments on all the time. DO YOU LOOK LIKE JAY CUTLER? WHY NOT? YOU TRAIN LIKE HIM! SOME OF YOU JUICE TO THE HIGH HEAVENS! How come you dont look like Jay Cutler then? Because you dont have the bodybuilding genetics of Jay Cutler, just like that powerlifter over there who can squat bench and deadlift a house can only build muscle mass to what his MOM and POP's unique genetics allow him to do so. So next time you build your argument on that above base take yourself to task also, look in the mirror and ask why your physique gets absolutely smoked by guys that you train and juice like.
2) Simple hypothetical question for you and im going to make it laughable by making it very high reps even to drive home the point.
Ronnie Coleman and Ronnie Colemans twin decide to start bodybuilding........
Ronnies twin decides to be somewhat comfortable and likes to stay in these ranges
Incline bench 135x185 for 8-12 reps for his career
military press 135 for 8-12 reps for his career
close grip bench press 135x185 for 8-12 reps for his career
lat pulldowns 150 for 8-12 reps for his career
deadlifts 135x185 for 8-12 reps for his career
standing calf raise 90 for 8-12 reps for his career
leg curl 75 for 8-12 reps for his career
squat 135x185 for 8-12 reps for his career
dumbell curl 20-30 for 8-12 reps for his career
reverse curl 25 for 8-12 reps for his career
Ronnie on the otherhand decides to go out of the confort zone and decides to push limits and accomplishes the following
Incline bench 405 for 15 reps
military press 335 for 15 reps
close grip bench press 415 for 15 reps
lat pulldowns 365 for 15 reps
deadlifts 550 for 15 reps
standing calf raise 600 for 15 reps
leg curl 240 for 20 reps
squat 550 for 20 reps deep
dumbell curl 100 for 15-20 reps
reverse curl 100 for 15-20 reps
Please tell me thru the adaptive process which twin is going to end up much bigger.........
3) Your unique genetics thru your mom and dad allow you to accomplish certain things in bodybuilding. If your mom and dad are Roseanne Barr and Jim Carrey let me be the first to tell you that most likely you are not going to be the next Sergio Oliva..... If your Mom and Dad are Lenda Murray and Lee Haney.....let me be the first to tell you that just about anything you do in bodybuilding training wise is going to build muscle mass.
but............. the absolute strongest YOU (yourself with your unique musclebuilding genetics) can make yourself in whatever rep range thru trial and error you find out is the most productive (20 reps, or maybe 15 reps, 12 reps, 8 reps whatever....) on safe progressive exercises is going to create the biggest YOU as a bodybuilder (again according to your unique musclebuilding genetics handed down from mom and pop)
So if you find out over time and chest workouts that you grow incredibly well from flat dumbell bench presses TAKE IT TO THE BANK THAT the day you can press 150 pound dumbells for 20 reps that your chest is going to be much thicker than if you decided for some weird reason to stay at 75 for 10 reps for the rest of your career.....because you were lazy or just wanted to train at 50% capacity