I'm curious: what's the reason for doing this rather than just logging the IP addresses that hit your server directly? Is this a way to get around VPNs that lea

I'm curious: what's the reason for doing this rather than just logging the IP addresses that hit your server directly? Is this a way to get around VPNs that leak the real IP via DNS? Or does this allow you to get something back from users with ad blockers that block the request, but no the DNS lookup (I don't know if this is the case)? Is it just a performance optimization (just a DNS lookup vs. a HTTP request)?