In the past, I didn't bother with mirror sites and and all those years from 1995 on were lost. (and please don't send me emails about way back sites and all that. At best they have fragmented info and the network has deleted all the real meat and potatos. )
What I've found with the way back web archives site is that some former websites are bought out or taken over by the network and used for parking sites with ads. Then whomever took over the former sites enables the robots.txt (on some sites), so that when you try to search the site via web archives, you get the error msg that the site's owner has blocked it by enabling robots.txt. Which then the former information is either deleted or blocked totally. That's how that works. Not all parking sites do that, but alot of them do. This is what I have found in searching old sites.
And then the older years of some sites that are allowed some viewing (parking site or not), have most of the pictures x'd out. Otherword, the famous red x meaning the pic wasn't saved or hosted. Otherwords, the fragmented sites, as mentioned in the Daily Messenger post.
We used them, as well, to find old, dead or deleted exemption forms links, and we started to run into similar problems. Robots.txt, blocked links, parking sites, link wasn't saved, or some stupid random bullshit thing.
What used to be a decent source, no longer is. Web Archives was taken over a long time ago, when they discovered that people were gathering old information, and found a way to stop it by network assets buying up old sites and parking them and basically wasting web space.
This is what a parking site looks like, using DB's old site as an example.