I spent a recent chunk of my career combating fraud on a niche-eBay style site and the people trying to defraud other users, pay with stolen credit cards, login with phished credentials, etc were consistently trying to hide their origin.
Until we started using fingerprinting techniques to track them across multiple accounts and IPs, we had no way to spot this. It was a shock to me when I realized there were legitimate uses for fingerprinting technology because I'd always associated it with ad networks and trackers. They're fairly necessary for combating fraud though.
When we stopped letting any untrusted users run a credit card if their connection couldn't be trusted, our charge backs virtually stopped. That experience makes me completely understand sites scrutinizing anonymized traffic.