> It's probably harder to tie devices in a single household together with IPv6 than with IPv4, or so they think.

It's probably easier, in fact. A significant and growing number of households are behind CGNAT on IPv4 and not have a 1:1 household : ip address relationship. On the other hand, if they're on IPv6, they're most likely on the same /64.

But, Roku's not doing IPv6 was handy for me when Netflix decided not to accept IPv6 connections over Hurricane Electric tunnels. I didn't have to change anything, and I didn't have to do anything, the Rokus were already ignoring IPv6.