RE: archive.org - the wayback machine for websites

No, this site it's just a database saves from some specific websites ( well known ) their xcode ( it's mean the origine code or file.html ) and put it in archive.org
in some sort, it just take images of the site and store it, until someone want an old version of the website ( sometimes to download something, the owner of the website took it away from the new version, but when you use archive.org to go back to the old version, you may have the possibility to download it )
so it can't be helpful in case someone took down steemit ( or hacked if this what you mean )

PS : try this url to see steemit on 18/08/2016 http://web.archive.org/web/20160818023804/https://steemit.com/

==> It just gives you the possibility to see the past, not to change it

I hoop i did answer your question, because i'm just a beginner programmer so you may find someone else who can explain this for you better than me