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)