Missing names on user list

I notice some people like Bill Stamper aren't on the user list any more. What happened?

I figure if they're inactive that would simply be reflected in the last login stat.

Did they have their accounts deleted? Did they remain in the system but taken off the list somehow?

I'm guessing these missing users still have their bills in the system as guest.
The bills entered for the top 25 users add up to 587,652 (with a few thousand more for the rest of the site).
The site total is 794,413.
The sum of user totals should be higher because of registered users hitting each other's bills.

Users expire from the list after 365 days of not logging in. Should they log in again, they will reappear. Their bills are not deleted and if you had a link to their profiles, you would see the correct count of entries and hits.

The total bill ENTRIES is probably correct, since one or two big enter folks (like Darryl) have fallen off the reportable list.

Bills HIT from one user to another might be something else entirely. D. Dave and I have hit about 20 of each other's bills. They all seem to be accounted for on my profile, but might not be (for whatever reason) site wide.

Okay, it is inactivity. Sorry for not using Stamper's full name.
I mean that adding up the individual user totals would be higher than the site total.