Exactly. I use to work with a company funded by Benchmark that approached it the exact same way. Their first game was just the start, and most definitely not the end. A lot of game designers fail to understand this; very few game empires are built upon a single IP. The half life of most games is pretty dismal.
Our angel investor runs a social gaming company backed by Sequoia, his company approached it in much the same manner. They have a backlog of game ideas. It's growing a big gaming businesses with multiple IPs that interests VCs, nobody wants to juggle the risk of game development on a single IP.
So yeah, the title of this post is definitely wrong. They fund game companies not game ideas.
It's like the gold prospectors. For the most part, the people who really got rich off of prospecting weren't the prospectors, but the shopkeepers, hotel owners and the like who generated great profit from the gold diggers.
So, it's the enablers of such high value but short life products that are truly valuable.
They're working on building out a platform that they can use to publish other games that handles things like virtual goods, payments, chat, etc. All of the myriad of things that go, in some combination or other, into every mid to hardcore game.
Also, social gaming companies, which have been receiving a lot of funding lately, are doing much the same. No particular game is their bread and butter. They're all working toward a full portfolio of games and usually have a lot of shared technology between them.
The title here is a bit of a misnomer. They fund gaming companies. They don't fund games. There's a big difference.