> Those phones are reaching half the internet via 64 gateways, no difference to reaching via 44 gateways.

And how would they have gotten first-hop connectivity without IPv6?

Comcast added IPv6 many years ago on their wired ISP side because they ran out of IPv4 for TR-069 management, and they had way fewer subscribers (at least at the time) than many mobile telcos.

And that half of the Internet is also some of the most bandwidth intensive stuff: Youtube, Netflix, Instagram. The CG-NAT hardware costs of streaming would be huge.

The network isn't just the open internet. There's also the part inside the network. You can view Comcast as a black box that magically gets packets from one side to the other, but Comcast engineers can't.