Except when they intentionally exclude websites. I have an ambivalent view towards the people who run the service.
Parts of internet history are lost forever because of arbitrarily removing and excluding archives.
For example, the abandoned Flash animation cartoon series from 2001 titled "Ninjai: The Little Ninja" has all but been memory-holed. (They won't even let you visit the archived website, regardless of the cartoon videos! Whom does that really benefit? I don't want to cuss, but I have unkind words for such people.)
This was a part of internet history. A quaint corner of the online world during the maturation of Flash animations. If it hadn't been for some stranger uploading the cartoon to a peer-to-peer network, it may have been gone for good.
(Someone did upload it to the Wayback library, but it was deleted. Someone uploaded it again, in a different format, and it might soon be deleted if it gets flagged.)
Let's just say, my NAS and backups are a safe home for some nearly-extinct gems of the internet.