I mean, there are insurance and retail stocks that have billions in revenue, showing serious profit each quarter and their share price is half of Twitter's. But, to be fair, Twitter didn't 'growth hack', they did build something people wanted to use. But their exit (as of now) would have to be considered 'gaming the system'.
Found this while Googling for Quora's valuation: http://techcrunch.com/2014/04/09/quora-forever/
Take the case of Quora. Quora is a question-answering website. You type a question and a domain expert might answer it for you.
Quora's declared competitor is Wikipedia, a free site that not only doesn't make revenue, but loses so much money they have to ask for donations just to be broke.
Recently, Quora raised $80 million in new funding at a $900 million valuation. Their stated reason for taking the money was to postpone having to think about revenue.
Quora walked in to an investor meeting, stated these facts as plainly as I have, and walked out with a check for eighty million dollars.
That's the power of investor storytime.
So yeah. No one games anything here.
I think the most dramatic example of this (other than WhatsApp) is Snapchat.