Well, Yahoo was designed to be a web directory, which eventually evolved into portal (until mid of 2000, Yahoo search would still show "directory").
Google was all about search at the beginning. I still went to Yahoo and MSN for news and information. But I think some time after mid 2000, a lot of folks began to shift from going to portal to get information, to typing keywords "news" in Google search. Somehow we are hooked to typing keywords. When Google finally released news.google.com now users could have a quick navigation of current events. This behavior is manifested in the era of social media. So many people are now getting news from logging onto facebook / twitter. To verify, as a smart reader I would search on Google, hoping to find a full version from reputable news sites.
In some countries/culture, portal is still preferred. e.g. Yahoo Japan being one. There are still some values of Yahoo.com; I still go there if I am looking up finance news or some pop-culture entertainment news (no other new sites do better than Yahoo on entertainment news broadcast).