There is nothing about IPv6 that prevents ISPs from filtering ports for all customers. They almost all actively filter at least port 25, 139 and 445 regardless of the actual transport. So I'm not sure "blocking service hosting" is the actual goal here.
The problem seems to be that all of the large and wealthy nations of the world have made the necessary huge investments into IPv6 while many of their smaller neighbors and outlying countries and islands have struggled to get any appreciable deployment.
It should be a UN and IMF priority to get IPv6 networks deployed in the rest of the world so we can finally start thinking about a global cutover.
