The MA50 and the MA200 are very important indicators and also resistance and support points, the reason why a MA doesn't move even if you see a 50% fall or run up, it's very easy, if the line is the moving average of the last 50 days, it will incorporate the ups and downs very slowly, because as the name indicates, it is an average, the average try to stay always in the middle of the price movements, one more reason to move very slowly.
They are very important because they have a psychological effect, when a stock breaks the MA200, this is a very strong long-term buy signal, an MA50 is more a short or middle-term buy signal.