But, clearly that's not what's in play here. It's difficult to be an open source startup because it's easy to get a big ego and start doing software wrong. You don't get people to use your software by saying "LOOK! We have VCs. Trust us. Buy our support contracts!"
You get people to use your software by making good features, growing by word of mouth, then you're entrenched and can start milking the support cow. Your word-of-mouth features don't even have to work (coughmongocough), they just have to be easy to brag about so developers get ego boosts by telling others "hey, look, i found this thing and you should think I'm cool because I'm telling you about it."
Another really important point: open source companies aren't proven. The current crop of open source startup VC funded happy towns are all experiments. It's very possible you can't create sustainable open source software companies (support contracts aren't zero margin software products, and nobody buys software anymore because lol "it's free!!!"). There's no natural "supernormal profit" engine if you make a good, clean, understandable open source product. In fact, it's actually the opposite: open source companies get big when the product is garbage (or too complex) because then everybody needs support to CYA against higher management.
(I've been thinking about writing a few articles about all this in January. Stay tuned.)