The author says Archive.is's claim that it causes problems is "questionable", but he doesn't mention what those purported problems are or address why they're illegitimate, so it's hard to evaluate whether that's accurate.
https://twitter.com/archiveis/status/1018691421182791680 (screenshot: https://aws1.discourse-cdn.com/cloudflare/original/3X/8/2/82... )
Hiding ECS from DNS queries seems to mostly just further create imbalances between companies that can afford routing at the IP level over companies that want to do cheaper routing at the DNS level.
(And like, if you attempt to directly mitigate the final IP problem by using a VPN or CG-NAT or something, that same solution will work for the DNS resolver, so I really am seeing no benefit.)
>1.1.1.1 is delivered across Cloudflare’s entire network that today spans 180 cities. We publish the geolocation information of the IPs that we query from. That allows any network with less density than we have to properly return DNS-targeted results.
Cloudflare makes an exception to this rule for Archive.{today,is,...} domains. All queries for this domains come from Amazon EC2 in the U.S., not the 180 edges of Cloudflare. This was on blog.archive.today. Why? Who knows. But the decision to break up is made by both parties, not just the archive.
There was another answer I could not find quickly where that is named here "another free dns service" was named Amazon.