More to the point, I've no doubt that some Yahoo employees have likely investigated this sort of tech and built prototypes, only to get shot down by middle management.
I've no special insight at Yahoo (had a couple friends work there) but for any sufficiently large company with employees as talented as Yahoo (YUI, YQL, etc) this has surely happened. So... to have your idea/prototype/demo shot down, then later $30m spent on essentially what you'd offered the company for free... that's gotta be frustrating.
Again, pure speculation that this had happened, but I'd be surprised if no one internal to Yahoo had floated/demos something like this before. They certainly could have bought some of the hype (stephen fry, etc) during a rebrand. But... instead, they buy from outside vs using and promoting internally.
Once more - just speculation, but that's were I would suspect frustration would come from.