[ChuckMcM]

Fundamentally it is the magnitude. Web sites often manage themselves to a metric called "RPM" or revenue per thousand. It can be thousand 'views' or for people who are interested in accuracy per thousand 'visits'. Unique IPs often translate as a good metric for 'visits'.

So if your traffic is 1.5M uniques and drops to .5 uniques, then your revenue may also have just dropped 66%. If you were staffed to be cash flow positive at your previous traffic rate, you now find yourself burning cash at an alarming rate. Your response, dictated by your reserves, is either lay off a bunch of people to curb your burn rate, or delay your accounts payable, or both. If this happens at an 'inconvienient' time, it can sour acquisitions in process, or deals with initial outlays, to be blunt it can kill you.

So then here is the thing, Google has no good way of knowing how you got to your organic ranking. There is no 'what is the rank of this place without these links' sorts of computations. So there isn't a good way to judge. But judge they must, lest others abuse their algorithm, and so they do so.

Now lets speculate that they kill off Rap Genius. Overall what does that do? Who does it help? Is it justice?

Lots of thorny ethical questions, not many good answers. And no way to make restitution. A sad place to be.