Sure, you can quote a short proof. But again, that's a niche solution to a niche problem, and it defeats the purpose of having citations. It also doesn't convin

Sure, you can quote a short proof. But again, that's a niche solution to a niche problem, and it defeats the purpose of having citations. It also doesn't convince anyone else that they should believe the proof you've cited. Archive.org is not a solution to this problem. Nobody is going to go fishing in archive.org for a citation that has disappeared. Even if you have the URL, what is the correct date to use? There are just practical problems with link citations, and you don't need to invent malevolent intent to understand why researchers are reluctant to use them.