You have users who can already access a site using IPv4, but want to use IPv6, and you have an anti-abuse system that lacks support, so you decided to invent a

You have users who can already access a site using IPv4, but want to use IPv6, and you have an anti-abuse system that lacks support, so you decided to invent a new kind of NAT, rather than require the customer to just fix their anti-abuse system, which they'd need to do on other platforms anyway? The feature isn't nuts, but the rationale seems so.