I suspect tracking and analytics are also part of the problem. Imagine every single IPv4 IP ban now being rendered entirely and utterly useless. DRM/Geolocation

I suspect tracking and analytics are also part of the problem. Imagine every single IPv4 IP ban now being rendered entirely and utterly useless. DRM/Geolocation blocks are also common and IP's are used quite widely in many software systems, most are likely to only accept a v4 address/format (perhaps terrible regex too). Detectives and other governments rely on IPv4 addresses as part of 'evidence', and storing V6 uses more storage and is much more complicated generally due to the much longer address space. We won't see the internet migrate to IPv6 entirely for another 20/30 years from now.