Port forwarding is nice, but everyone already knows you can hardly run a server at home (even in countries where port forwarding is standard). It's been this way for as long as I can remember. So yes I handwave it away because it doesn't matter. If that's the only drawback to CG-NAT (other than single IP address bans applying to entire nations or something) I hardly understand why it warrants treatment as such a terrible awful disaster.
I will raise you the opposite point: why deprive people of their ability to have a globally addressable IP address?
>But even UDP should work through CG-NAT.
I have already told you why it is wrong to make such as assumption, haven't I?
I have heard of stories coming from China and Vietnam that some ISPs implement so-called "type 4 NAT", otherwise known as symmetric NAT or NAT with endpoint-dependent mapping.
This kind of NAT is NOT hole-punchable. And because you don't control the NAT, you are simply SOL if one day your NAT decides to switch to it. Can't even use Tailscale without significant service degradation now, ouch.
Granted, I have only heard about it in Vietnam and China, and it's not a national thing -- only some provinces seem to have symmetric NAT implemented. But I feel the need to remind you that the ISPs there were able to get away with it, because the two countries have significant IPv6 presence. [0]
>Port forwarding is nice, but everyone already knows you can hardly run a server at home (even in countries where port forwarding is standard).
You can hardly run a server at home because we have been facing address space depletion since the dot com bubble.
>I hardly understand why it warrants treatment as such a terrible awful disaster.
You haven't faced an overloaded CGNAT gateway, have you? [1]
[0]: https://stats.labs.apnic.net/ipv6/XD
[1]: https://www.reddit.com/r/ipv6/comments/1as8dvy/is_there_a_wa...