Hacking (aka guessing the password?) 3 accounts from the same age is not very likely. It could also be they're all from the same owner, although I see no reason why someone would have created 3 accounts to a brand-new forum back then. It could also be the first sales-tread reminded other old-account-owners to sell them.
Even if they're hacked, the original owner clearly doesn't use them anymore, although that should be "frowned upon" no matter what.