Comment by MerManMaid

IPv4 as well as IPv6 was designed with endpoint to endpoint communication in mind so when NAT was conceived (originally intended to be a stop-gap while we moved to IPv6) we also had to re-write many other protocols and create many new ones since NAT broke IPv4's design principle (each IP needs to be unique)

This has lead to many context specific problems as many of the re-written protocols don't work as well not to mention the added complexities of protocols designed specifically with NAT in mind. As another network engineer I can attest to the problems this has caused. Pretty much everything from overlay VPN networks, VoIP solutions, security and ACLS, and just our day to day maintenance tasks are complicated by NAT. It has gotten so out of hand that many of us have dedicated NAT routers just handling NAT translation.

It's so weird to me that so many people in our industry spout scalability but then laugh off IPv6... How the heck do you guys plan to communicate to the ever increasing amount of smart devices? IPv4 literally ran out a space years ago...