Yahoo didn't necessarily fail - it's just not their core purpose/business. Their name/brand recognition exists, but not for auctions. Yahoo's auction site is still around, but when you think about online auction sites, eBay instantly comes to mind in undoubtly 99/100 people. It doesn't matter what kind of technology Google uses - eBay has a viable prescence and Google would have to offer something unique and get a lot of press in order for theirs to even make a dent in eBay's business.