I guess they need to simplify their routing tables to avoid hitting size limits? As v6 gains traction (does it?) it will become more of an issue.
Discussion
I don't think this is an issue for IPv6 in foreseeable future. As seen by our network (AS215467), fullview for IPv4 contains 972711/970267 routes and IPv6 only 206989/212113 (Poland/Sweden accordingly)