I say the same thing about people who track their body fat. Who cares if its 15% 0r 10% or 5%. Just look in a mirror.

Yes. I agree. Only for people who are entering a weight training program and are severely overweight this can be difficult. At first it is very hard to tell if you are gaining any muscle without monitoring body fat.

I am not saying it is necessary by any means. However it can be discouraging not to know if you are making any progress when looking in the mirror doesn't show the changes.