Some guys just change their lives or get new tasks in their jobs or...
Nobody can expect that anybody has the same interest in the game for more than a day or a week.
Limiting the White Rabbits CC by language, I once was glad to accept the request of any guy with the right flags. There were plenty of inactive players from three years to replace, but about 120 entries later nothing has really changed: Many inactive players...
I learned that many of the Hacks and Amateurs would only play for a day or a week before turning away from the game. One guy even has NOT played a single game since he joined the CC.
I leave them in because I like to have a big CC, but I refuse entry for Amateurs and Hacks most of the time now. Instead, I propose that they become Pros and apply again. Unfortunately, most of them find another CC instead.