The claim was that it made it worse. How is sharing the same /64 worse than sharing the same IPv4 address? On top of that, you don't actually know that it's a

The claim was that it made it worse. How is sharing the same /64 worse than sharing the same IPv4 address? On top of that, you don't actually know that it's a /64. The customer could have a /56. The customer could have a /128, which some mobile ISPs do. The customer could have a /128 with the ability to request arbitrarily many of them from the ISP, allowing the same trick with one IP per outgoing connection but causing the pool to be shared across all the ISP's customers. The ISP could, in principle, allow the customer to request an arbitrary number of non-contiguous address ranges of an arbitrary size and use them for an arbitrary duration before reassignment to a different customer. Nothing really requires it to be a single /64 forever.