Sites and services often rely on a lot of IP-based filtering and categorization, at the firewall level, to fight abuse and attacks. Routing IPv6 makes that more

Sites and services often rely on a lot of IP-based filtering and categorization, at the firewall level, to fight abuse and attacks. Routing IPv6 makes that more challenging. Dropping all IPv6 connections makes it easier. So, if you think you can get away with simply not serving requests from IPv6 addresses, it's tempting to do.