A lot of people try out the game for an hour, for a day or a week and never come back. Some even apply for a CC before they play their first round and are only deadwood in the next second.
As a CC owner, I don't want to have more deadwood from any obligation!
Furthermore, life is a constant change. This is a pastime, made for fun, so the interest for the game comes and goes after any thinkable time if the fun ceases. More deadwood in the CCs.
Any owner who wants his CC to grow must be attractive to his members, providing some of the fun which motivates them to stay and play. This includes tourneys and other events, communication, cameraderie, excitement. I like the quote of Mr. Saint-Exupéry about the desire for the seas necessary to set up a ship-building crew...
PSUTOM: I give them the benefit of the doubt thinking they might be practicing before they dive right in to the tourneys.
No need to guess. You'll see any activity, any finished (practice) game, in the "date last played".