It happens in the stock market too. When a leader starts to move, the followers move with it. Natural tendencies that aren't unique to crypto. With that said, because we are so young and small, the movements can swing violently when our posterchild, BTC moves, particularly with the Altcoins since most of them require BTC to buy them. Once there is a more level playing field and a decoupling of BTC to Altcoins I'm guessing we won't see the market sway with the same ferocity. Lets' see