FIDE's 'Not Rated' Players

Two weeks ago, when I first looked at the FIDE Rating List - January 2016, I noted,

The main download page, FIDE Download Rating List, offers six different lists:-
* Full list of players (not rated included)
* STANDARD rating list
[...]
Last year I decided to stick with the 'STANDARD rating list' and this year I'm doing the same. Some day I might look at the 'full list', but I don't have the time or the interest for that now.

I haven't found the time to take a proper look at the full list, but I have found the interest, so I downloaded it (Thanks again, FIDE!) into a database. The first thing I noticed was the size of the list. It has 560.640 players, while the STANDARD rating list has 231.238 players. How do those >300.000 unrated players break down by federation? The following table shows the federations with the largest number of 'not rated' players.

Count by federation of players with:
'S' = standard rating
'R' = rapid rating
'B' = blitz rating
'<>' = no rating

The counts of standard rating don't quite match the counts in the previous post -- they are a generally a little higher -- but I didn't download the lists at the same time. The difference isn't enough to bother me.

To double-check my results, I looked at the USA players with 'no rating'. None of the 8336 players were marked inactive and a few of them had CM/WCM titles. About 30 had FIDE Online Arena (FOA) titles. Many of the players had FIDE IDs that looked unusual to me.

Why is FIDE interested in keeping track of so many additional players? That is a question for which I have no answer unless it's something to do with FOA.