NAT / CGNAT has been doing the heavy lifting extending the life of the Internet; ipv6 has done jack shit. If v6 was useful and actually averted v4 exhaustion we'd all be accessing v6 sites/addresses at this point.

Put another way, we can drop v6 completely and the Internet will still work. Obviously wouldn't work the other way around.

As for telco addressing handsets, they could use any addressing scheme to be honest. When people talk about averting address exhaustion, they're not talking about internal addressing of networks, different problem altogether.