I am referring to this post: How many users are there on Stack Overflow?
Why do the two solutions (API and HTML peek on newest user) seem to give incongruent numbers?
What you have termed the "HTML peek" method which is just looking at the user id of the latest user off the user roster sorted by creation time shows you the database user ID number. This is just an increment value. This means placeholders have been created for X number of accounts, it doesn't actually mean there are that many users now.
The API gives you a more useful number of actual current accounts.
I said "placeholder" earlier because often those are actually anonymous unregistered accounts that have not been bound to login credentials yet. It is not uncommon for folks to drift by and end up with several of these unregistered accounts before they discover that in order to maintain access to their account it makes more sense to register. At this point there is often a merge between any duplicate unregistered accounts.
But there are many other scenarios where an account may no longer exist. They may have been deleted for one reason or another.
To make a long story short, there is no discrepancy but you have to know what the numbers mean. An incrementing counter number on account creations != current number of users.
Here are the current counts for Stack Overflow: