A number of them are. Especially when you get out of first world countries. The problem is that folks who deploy them really hate scaling them up. They believed in IPv6 and the transition isn't going fast enough (sup hosters and cloud providers - stop treating IPv6 as a "customers aren't asking for it" problem and realize this is infrastructure you have to do on their behalf). So now they are stuck paying for v6 CGNAT upgrades or in some cases: running them congested.