Remember when Google was trying to fly under the radar because they were afraid that Microsoft would find out how much money they were making selling ads on search result pages. Anyone knows if any company is doing that today? It seems we only know about start-up companies through PR pieces (oh pardon me, I mean objective journalism of the highest quality).
Kickstarter and Cloudflare - both have been keeping all their financials in the secret until they have murdered most of the competition.
Most of the users would come from word of mouth.
I feel like that's almost impossible to do today especially with enterprise products (e.g. google selling ads to businesses). I think people now are accustomed to using products they've come across online and anything else is too foreign and strange.