The low Ipv6 domain adoption is due (in my opinion)
To not every one have Ipv6 so in your dns you need to have ipv4,to not lost this audience.
After it can be related to protection system like waf.
The majority of isp give a /60 cidr to every one so it's easy to have a lot of ip. Some company like cloudflare have a mapping system from Ipv6 to ipv4 (of course with a lot of collision) and low number of procetion service provide a good detection system for Ipv6 one
So majority of system in customer stack is not ready for Ipv6
I can understand you will not consume some time for low number of benefits.
To not every one have Ipv6 so in your dns you need to have ipv4,to not lost this audience.
After it can be related to protection system like waf. The majority of isp give a /60 cidr to every one so it's easy to have a lot of ip. Some company like cloudflare have a mapping system from Ipv6 to ipv4 (of course with a lot of collision) and low number of procetion service provide a good detection system for Ipv6 one So majority of system in customer stack is not ready for Ipv6
I can understand you will not consume some time for low number of benefits.
(Ipv6 it help a bit all tracking system )