> why the internet archive even exists

As an archive that supplements my personal archive, and the archives of many others. Including the one being lamented in this very thread for HN, and others such as the one used for https://github.com/afiodorov/hn-search

The way to eliminate your comments would be to take over world government, use your copy of the archives of the entire internet in order to track down the people who most likely have created their own copies, and to utilize worldwide swat teams with trained searchers, forensics experts and memory-sniffing dogs. When in doubt, just fire missiles at the entire area. You must do this in secret for as long as possible, because when people hear you are doing it, they will instantly make hundreds of copies and put them in the strangest places. You will have to shut down the internet. When you are sure you have everything, delete your copy. You still may have missed one.