auth will help relays avoid having to rate limit by IP address ( a terrible, horrible, and frankly useless method of fending off greedy connections). instead you can use your npub with auth, and either stay within a regular client usage tier, or pay more to go insane with queries. i do think most if not all relays will do this eventually, or theyll end up exactly like every website that blocks and captchas vpn connections. (even free relays)
fiatjaf hasn't even considered that clients could be configured to make a new key every auth request except for to paid relays also, defeating the privacy invasion angle completely and pointing back to the IP tracking problem
i just think he's in denial about the fact that relays are inherently trusted third parties, and reconciling that with the "free anti-censorship" features a relay requiring auth to post is not censorship, and without auth you still get an IP address, and if that's a VPN address spam from such a vector will blanket block all use in this way paying for use of a relay doesn't doxx you... that would require using a doxxable payment route and not using tor/vpn to access the relay so, ip/npub as ways to decide what will be stored and relayed are both inevitable mechanisms, and being against censorship does not also mean being against paying for the goddang infrastructure lol