The first RFC for IPv6 was published by Xerox PARC in 1995. This was right before the Internet started to grow exponentially, so I can imagine the people who de

The first RFC for IPv6 was published by Xerox PARC in 1995. This was right before the Internet started to grow exponentially, so I can imagine the people who designed it was not planning a super soft/organic transition, and they probably considered that good backward-compatibility with IPv4 would be too hard and not really necessary.