While I mostly agree with the idea, I dislike the appeal to original intent that often comes along with insisting "well direct device to device addressing is the way the internet was originally designed."

And its like true, but also the internet wasn't built with the intent that my fridge, lightbulb, etc were all gonna be online either. Of course the solution is a sane firewall not NAT, but similarly all of that is beyond the original scope as well, such is life.

In any case, ipv6 is an easy qualifier of several for me to apply stronger anti-bot checking, without really impacting my intended audience. Of course geolocation, ASNs, alleged user agents, etc all weigh in too.