With always-on routers usually being the DHCP lease recipient for residential broadband, even dynamic IP addresses are typically a lot more "sticky" than most people expect. Couple that with the location-specific info available via reverse DNS on residential IPs, and it doesn't take a vivid imagination to see how easily even a loosely correlated search history could be used against you when applying online for jobs, healthcare, credit, etc.

I would honestly be shocked if there aren't risk assessment departments (or entire companies) already specializing in applying techniques like that to filter resumes, bias interest rates, and raise premiums accordingly.