I think this would likely be most troublesome on some of the OG internet users that got a whole freaking /8, /10, or /12 or something like AT&T or universities. Up until very recently, and possibly even to the present, these organizations had such large IPv4 space, that there was no need to do NAT, and each device had a publicly addressable IP.
https://en.wikipedia.org/wiki/List_of_assigned_/8_IPv4_address_blocks
https://explainxkcd.com/1084