This is a really great way to divide up the ecosystem. And you're right, it's mostly eyeballs or teams for sale in "traditional" startups (if you can say there is such a thing).
So few people in the startup ecosystem sit down and think hard, "Where WILL we make our money? What do we REALLY have to sell?" So many assume that they will get bought because "they have a great product" or "they are the best" or "they have traction," but honestly, that's not even why most bigco's acquire startups. As you pointed out.[1]
This is not a disease of startups alone, of course. Most employees never sit down and ask themselves how & where they create value for their employer, much less how much, and whether they're then earning too little or too much. They just stab around in the dark for a number they think they deserve.
But when an employee gets the value equation wrong, worst case scenario is he/she loses a job. A whole company, product, ecosystem doesn't go down the tubes.
(Sidebar: It really warms my little bootstrapping heart to see this becoming a serious discussion topic lately!)
[1] There are other factors I'd add -- sometimes, it seems like a bigco buys a startup because they have too much M&A budget and simply want to fill a slot, check a genre off their list. "Can't buy Twitter? OK, buy Jaiku and call it a day. tick" Or the ever-popular "this little company annoys us so we'll buy it and kill it so we can stop thinking about it" technique, which sure as hell seems to happen far more than startup cheerleaders will admit.