In many instances, this can be helpful. For example, if you are searching “bass”, Google might list websites related to bass guitars if it knows you are a musician, or list websites related to the animal if it knows you like to fish.
However, this feature can be very problematic for student research. If a student needs a broad range of sources that are positive and negative about a certain issue, Google may instead list websites that tend to portray only one side of the issue, particularly if it already “knows” which side you agree with. This leads to even more “silos” of information rather than providing a balance view of controversial issues. It is a concern to librarians, and hopefully to students as well.