Diverting investors' capital from the startup they picked into another startup providing B2B services would be a legitimate concern. But is this actually happen

Diverting investors' capital from the startup they picked into another startup providing B2B services would be a legitimate concern. But is this actually happening enough to even move the needle for YC? Their past or most likely successes off the top of my head have been Reddit, Dropbox, and the AirBnB spammers, all of which are primarily B2C and don't have other YC startups as major clients. I also wouldn't expect any viable startup to live or die by their prominence on HN; this audience is still small and mostly frugal, more likely than anyone else to conclude (sometimes falsely) "I don't need to pay for that, I can build it myself". This isn't very convincing even before the 20 IQ point penalty for encoding a page of text as a 72 KB image. Edit: there's a longer greatest-hits list at http://www.crunchbase.com/company/y-combinator http://www.crunchbase.com/company/y-combinator, and none of those look like major money sinks for other YC startups either.