Because there is nothing nor anyone to build off of. There is zero credibility or conviction in this. There is no way to know if this person stands to gain massively from the IPO. And who stays working at a place like this if you feel this way? If this were Russsia, China, North Korea etc and the person was speaking out against the state or this was someone in physical danger or being abused then by all means be anonymous. But odds are they suffer very little for coming forward. Uber will also ignore anonymous stuff like this. Come forward, go to the press, relevant officials and try to do some good. Or delete this article and move on.