It does not if there are common interests and characteristics among users. Let's say for example I'm a young African-American girl who wants to learn how to cod

It does not if there are common interests and characteristics among users. Let's say for example I'm a young African-American girl who wants to learn how to code and I query "how can African-American girl learn coding?" and Google shows me Black Girls Code a non-profit organization that focuses on providing technology education for African-American girls. Considering that Google knows that I'm African-American girl and that I want to learn coding, how many other African-American girls want to learn coding? Probably many so caching doesn't break customization and personalization as long as Google knows my characteristics and interests and characteristics and interests of other people that are similar to mine.