Not necessarily true. If the only muscle groups that get worked out are your pecs and triceps, you're probably not doing them right. Being able to do 100 proper pushups consecutively is no easy task and requires a lot of work from supporting muscle groups (back, abs, deltoids, quads and hamstrings to a lesser extent). Your core has to be strong in order to maintain the rigidity necessary to control the motion. Granted, if you plan on playing soccer, you'd still want to work your legs directly, but don't think that the rest of your body didn't benefit from doing all those pushups / benchpresses. However, those other muscles won't necessarily get as "bulky", as tension-type exercises don't generate that kind of result (think pilates).