Accounts that were never active will be filtered out anyway by the query.
You can find accounts that were never active when "last_vote_time" is equal to "created"
Finding unique account holders is not possible with querying the database in the current set up and may require more manual firepower.
That's right. There are some info in the post, like @noganoo - if I spelled it right - has over 1000 accounts. @berniesanders has at least 55 accounts. There was a spammer here that looks like he owns 2700 accounts: https://steemit.com/steemit-abuse/@patrice/2700-accounts-love-spam-comments-is-this-a-case-of-gaming-the-system-or-abuse
And more... When you filter all these accounts, you will see that there is a small percentage of active Steemit accounts.
How about pooling these account names together into a common Google sheet so that users can update there directly and avoid duplicating their labor? I will try to curate this next week.
Good idea!