Are lunges better than squats for building muscles?
Both the exercises are important in their own way. If I speak from experience, then lunges do a better job in tearing up your glutes than sqauts do.
And quadriceps also have 3 different muscles groups.
As you know one leg (forward) during lunges imitates a squat-like position. But the backward leg does a different job, and if done properly, it is the backward leg that will burn a lot more than you forward leg, and it taregts different group of mucsles.
Sqauts, lunges, leg presses and other leg exercises are designed to target every muscle group hard so that you can have a fuller-looking quad.
Just like we don't do only bicep curls to build big biceps and include a lot of other exercises like preacher, twisted curls, barbell curls, etc, legs also require different exercises so as to target the whole area from different angles.