Quote Originally Posted by Flip Skinny
You all confuse me here. Half of you think push ups are god, half of you think weights are the devil... wtf!?!!!

It comes from the old belief that weights "stiffen you up".
Yes, in a certain context. Training like a bodybuilder, curling here, extending there will shorten your muscles and make you not as sharp or fluid as a boxer needs to be.
But if you stick to big core exercises like mentioned above. Those that use a lot of stabiliser muscles, core muscles and force your muscles to work together, your body will only grow stronger, enhancing muscle speed, growth and strength. Something i think we all agree is a bonus.