It’s because this guy en.wikipedia.org/wiki/Prabhakar_Raghavan thinks that keeping people engaged on google search longer is what it is all about. Not finding what you search for, no, engagement with your search tool.

"He was the head of search for Yahoo from 2005 through 2012 — a tumultuous period that cemented its terminal decline, and effectively saw the company bow out of the search market altogether. His responsibilities? Research and development for Yahoo’s search and ads products.

When Raghavan joined the company, Yahoo held a 30.4 percent market share — not far from Google’s 36.9%, and miles ahead of the 15.7% of MSN Search. By May 2012, Yahoo was down to just 13.4 percent and had shrunk for the previous nine consecutive months, and was being beaten even by the newly-released Bing. That same year, Yahoo had the largest layoffs in its corporate history, shedding nearly 2,000 employees — or 14% of its overall workforce. " - www.wheresyoured.at/the-men-who-killed-google/