Because it affects earning estimates going forward, if they "beat", analyst can raise estimates looking out 5 years [so the results look like they are on track

Because it affects earning estimates going forward, if they "beat", analyst can raise estimates looking out 5 years [so the results look like they are on track to be way better than estimated], or vice-versa, when you miss you have to take down your future estimates of growth. Then its discounted to the present. Thats why it moves, its not about this quarter, its about adjusting all the expectations of the future down and to the present, all wrapped up nicely in a stock price.