Google is the #1 search provider, right? People trust their results more than all the others combined.

But by merging Yahoo and MSN search, you don't somehow double the search position. THEY'RE ONLY AS GOOD AS THEIR BEST ALGORITHM (which may be MSN). They still have to pick one search platform and go with it, and neither is even remotely as good as Google.

There may be some economies of scale at play here, but search ain't one of them. And that's still the ace card in the online deck.