I think it’s a great idea from a network monitoring perspective (https, no subdomains, archive.org serves pretty much the entire internet). In the past, we have also thought about GitHub pages as well.
However, before recommending that approach as a blanket technique to grab information from a landing page, we should obtain further details on archive.org (specifically their internal security and how they ensure page integrity as well details on what they log).
There is the unfortunately technical solution is to sign/verify signatures but not user friendly. I think the ultimate solution would be more distributed directory, multiple distinct external resources that can me compared.