What does this mean?
I don't know the reason, but everyone says do barbell rather than dumbbell. You can push more. Maybe that's the reason?
What kind of squat are you doing? I've tried every leg exercise known to man, and someone recommended doing low-bar back squat (rest bar on rear delts) here a month or 2 back, and that is the greatest exercise I've ever done. It fully stretches out your hamstring, glutes, and adductors on the squat down, which gets them in on the lift much more and ends up being a full-leg exercise. High bar (bar on traps) doesn't give that full stretch. My legs are 33-50% bigger in 2 months, no exaggeration (granted, I have/had bird legs).
Definitely add in deadlifts. Cleans are somethin I've done periodically but should be doing more of.