There are mirrors and backups of Wikipedia. Archive.org has no substitute.

archive.today at least allows people to preserve snapshots of selected websites, which is often important for being able to demonstrate that mainstream sources have edited or deleted content without proper acknowledgment.

Interestingly enough, Wikipedia once (I haven't checked if it's still in effect) blacklisted links to there, with compelling evidence (if you read any of the discussion behind the scenes) that it was actually about certain admins and power users trying to maintain control over the bias in main-space article content.