I still can't agree with what Page says about 'personalised results' though. He talks about 'search understanding you' as if it just makes existing search 'better'. But to me search is about 'I know what I'm looking for so I ask for something specific', usually looking for a fairly certain answer. If this involves my search history, or people that I know, I will be able to tell the search platform that when I search, I don't want them to assume this on my behalf - this just makes my results less specific than I originally intended.
Its a bit of a conflation between advertising and search really, they are trying to second guess what I am interested in before I know it, which I'm not sure is very positive.