That's not really the kind of bubble being talked about, and there are good arguments why a search engine should at least have some knowledge of search history

That's not really the kind of bubble being talked about, and there are good arguments why a search engine should at least have some knowledge of search history to implement conversational search and better understand what the search terms mean in context. If I just searched for "apple pie recipes", and my next query is "where to buy apple", I don't want to see a link to Store.apple.com