The price and, ultimately, the charts on any given exchange are determined by the price of the most recent transaction. How can the prices of 100s of cryptos all move in the same direction at the same time?
It is nowhere near as odd as it may seem, sometimes when a big and influential company releases their report and it is bad this can be more than enough for the stock market to have a bad day, now imagine if that the company behind such stock was so powerful that it was roughly half of the whole stock market, it had massive credibility and the rest of the companies were always trying to copy everything it does, do not you think the stock market will move according to the movements of that single company? And the answer is yes, which explains why most coins move in the same direction bitcoin moves most of the time.