Yes, it denies simple P2P connectivity. World doesn't need it. Consumers are behind firewalls either way. We need a way for consumers to connect to a server. That's all.
With IPv4 + NAT, you have a public IP address. That public address goes to your router. Your router can forward any port to any machine on your LAN. I used to run Minecraft servers from a residential connection on IPv4, it was fine. Never had to call the ISP.
In many countries they don't have enough, so you have CGNAT.
Still, I do think that the solution of, "one IPv4 address per household + NAT" is a perfectly good system. I view the IPv6 mentality of giving each computer in the world a globally unique IPv6 address as a non-goal.
For one, businesses and other entities also need Internet access. Cloud companies in particular needs a ton of addresses. That's gonna eat up a fair chunk of the remaining 50%.
Two, humanity is still growing, governments across the world are building new housing. That's gonna eat up another chunk.
Three, routing is hierarchical, and infrastructure organisations and ISPs are assigned blocks of addresses, not individual addresses. We can't just have a pool of free IP addresses and assign any address to any house in the world as needed. So even having 50% of IP addresses free wouldn't really be enough.
So in my mind, an IP addresses to household ratio of 0.5 means residential CGNAT is inevitable, even if we ignore legacy issues like individual universities and other institutions owning gigantic /8 or /16 ranges.
If you are giving out public IPs then you aren't really NAT'ing.
I mean, I understand that this feels normal today, that 10-20-50 devices need internet and that the way to manage that is to nat the connections, but your ISP isn't doing nat, it is you.
I also deployed it as a pilot on an internal network. Other than getting direct IPv6 connectivity to some services, which sometimes gave us better performance, it conferred no advantage to us.
IPv6 is great for phones where you don't expect any inbound traffic. Even then, every US carrier is using Carrier NAT to route and proxy traffic for their own purposes.
Either way, mea culpa.
Unfortunately, the internet is used for a lot more than using one of the six gigantic centralized websites.
Speaking of that, why don't we just keep ipv4 for ourselves and let them eat ipv6?
Worth pointing out that this article was written by the now-CEO of Tailscale. I don't know if "The world doesn't need P2P connectivity" is a compelling take.
I do wish ISPs would refrain from intentionally breaking things though. It ought to be illegal for them to block specific ports or filter specific sorts of traffic absent a pressing and active security concern.
I don't want our communications infrastructures to be just for consumers.
Roughly, it's my belief that an IPv6 world makes it easier for centralizing forces and harder for local p2p or p2p-esque ones; e.g. an IPv6 world would have likely made it easier to do bad things like "charge for individual internet user in a home."
The decentralization of "routing power" is more a good thing than bad, what you pay for in complexity you get back in "power to the people."
This idea comes up in every HN conversation about IPv6, and so I suppose this time it's my turn to point out RFC 8981[0]. tl;dr: typically, machines which receive IPv6 address assignment via SLAAC (functional equivalent of DHCP) periodically cycle their addresses. Supposed to offer pretty effective protection against host-counting.