Yes, accounts with no activity, no site contributions, community database link, and no posts, would definitely have been pruned at some point. That fits the profile of the infinite spam accounts we get. On a few occasions we have also pruned accounts with <5 posts, but no site contributions, community database link, and inactive for several years. Make a contribution
to the site or more than 5 posts and you're guaranteed an account for life. Or log on once a year.
Unfortunately, we do not have the technology to track wiki changes on the site accounts so they do not count. Under the hood they are still separate accounts that are bridged by third party software. As a result, the datacrystal wiki account should still exist actually, even if the RHDN is pruned. No one here has ever pruned datacrystal accounts (AnyoneEB may have prior to the RHDN merge) and there are no plans to do so at this time.