End to end connectivity without a third party server for discovery is either complicated for the end-user (manually specifying IPs, ports, etc) or it relies on inherently insecure techniques like multicast/broadcast. And once you introduce a third party server that both peers connect to, establishing a connection even through NAT is not that much harder. And yes, NAT does have some costs, but transitioning to IPv6 also does, and I don't think that the Internet justified that cost at the time IPv4 addresses first started running out. NAT's cost is much more diffuse and in the future.
We'll see if this more direct communication actually happens as IPv6 becomes ubiquitous, but I for one doubt it. Especially since ISPs are not at all friendly to residential customers trying to run servers, often giving out dynamic prefixes or small subnets (/128s even!) even on IPv6. And I think the LTE network is decent evidence in support of my doubts: it was built from the ground up with IPv6-only internally, and there are no stable IP guarantees anywhere.
As to the privacy benefits, those are real and have made IP tracking almost useless. Your public IP, even in the developed world, very commonly changes daily or weekly. Even worse for trackers, when it does change, it changes to an IP that someone else was using.
> establishing a connection even through NAT is not that much harder.
This is false. Because of the inconsistency of NATs and other middle-boxes out there and the fact that many are broken, it's far less reliable. You end up having to relay some traffic, which imposes external cost that unlike a third party locator server isn't trivial. Now you're already losing the benefits of end-to-end connectivity.
Also if E2E is easy there are distributed algorithms for location like DHTs that can be implemented. With trivial end to end they're pretty easy and would be fast and reliable.
The way the Internet has developed has basically broken it for end to end connectivity, forcing everything into the cloud. That is far worse for privacy and autonomy (and cost, making everything a subscription) than IP tracking.
I think you're a little blinded by what is and unable to imagine an alternate path.
Evolution is very path dependent and small changes at one point make things massively different later. One less asteroid and we'd be warm blooded bird-reptile like things that laid eggs.
Perhaps, but I'm not at all convinced. The hard problems of running distributed peer-to-peer services are not end-to-end connectivity. While that is a problem, it's a relatively small hurdle; you can connect the vast majority of clients with some not huge effort.
The much bigger problems are related to moderation, copyright enforcement, spam prevention, security. All of those are extremely hard if you don't have a centralized authority server.
Could Zoom have better quality more cheaply if it could easily do P2P connections for small meetings? Very likely. Could you make a fully distributed Zoom where anyone can call anyone else without a centralized authority server handling all calls? No, not without significant legal hurdles and effort on preventing malicious actors from spamming the network, from distributing illegal content, etc.
Also, back to middleboxes: not having NAT would not get rid of middleboxes. Even on IPv6, there will always be a stateful firewall blocking all outside connections to the internal network in any sane deployment, at least for home networks. And that firewall will probably be about as buggy as cheap NAT boxes are. And for corporate networks, you have all sorts of other middlemen critical to the security of the network, I clouding IDS and IPS systems, TLS listeners to protect from data e filtration etc. Those will interfere with your traffic far more than relatively regular NAT boxes would.
We'll see if this more direct communication actually happens as IPv6 becomes ubiquitous, but I for one doubt it. Especially since ISPs are not at all friendly to residential customers trying to run servers, often giving out dynamic prefixes or small subnets (/128s even!) even on IPv6. And I think the LTE network is decent evidence in support of my doubts: it was built from the ground up with IPv6-only internally, and there are no stable IP guarantees anywhere.
As to the privacy benefits, those are real and have made IP tracking almost useless. Your public IP, even in the developed world, very commonly changes daily or weekly. Even worse for trackers, when it does change, it changes to an IP that someone else was using.