I doubt we will ever know.

My guess is that many Square Enix employees (including devs) and community reps do actively play with their own characters -- but they are probably under contract not to disclose their affiliation with the company.

If it were known who their in-game characters are, then anything they say would be at risk of being taken as "official" word on what will happen with the game.

Perhaps many of them would find it difficult to join normal Linkshells because it would be difficult to keep such a big secret from people who become their friends.

So maybe that could explain the few people who have been playing regularly from the very beginning but don't belong to any Linkshells? ^^;