In IPv4, dynamically leasing different IP address by connecting is a mitigation of lack of address stock (at least dialup from PC era, I don't know how much eff

In IPv4, dynamically leasing different IP address by connecting is a mitigation of lack of address stock (at least dialup from PC era, I don't know how much effective in router era). In IPv6, ISPs don't need to do that so they can just lease dedicated IP block to customer. Then they don't need logging IP-to-customer-by-time for investigation.