Unfortunately, a lot of the remaining holdouts are just network engineers who just can't be arsed to learn anything new...

We had plenty of enlightened network engineers, but eventually government wanted some torrents to stop working. Torrents were installing 6to4, Teredo and so on and hoping to work this way. But government agents were doing checks. Government agents were checking WiFi networks here and there, and ISPs. And government agents also had those torrents installed, and they could easily enable 6to4, Teredo, all of that. As soon as any such loophole permits opening forbidden website, every party gets serious fines. So they were runnning circles in panic. And blocking, blocking, blocking.

That's how our dream of IPv6 died. We don't dream about IPv6 anymore.

Our network engineers do learn new things. How to block. There was no DPI, now there is. A new dimension of progress.