They changed the browser UI, either the browser devs or the site devs via stupid javascript tricks (messing with scrolling, etc). I got driveby download powned and my CC info stolen and five spam toolbars in the UI I can't get rid of. There are too many spammy ads. They make is as hard as humanly possible to use bookmarks to encourage the use of a search engine every single time you go to a site thus monetizing ad views. Typosquatters. "Journalism" sites with one line of the article per page of spam. Spam "answer" websites.
Memory is way, way down the list.