Cardio us "feared" by many because is can be quite boring, and the results you get doesn't appear in the shape of increased muscle-mass or shredded abs. Unless you are dieting and it gets you into a calorie-deficit that is. Thing is, if you want to maximise your muscle-building capabilities, spending a lot of time and energy on doing cardio can take away from your progress. If you could do 2 more sets per muscle-groups per week if you ditched the cardio, isn't it worth it? ~ Berceste