We had the exact same discussion last year among Quebec organizers and one of the answer was : the player and organizer pool has grown so much that more and more games were organized to satisfy a bigger player pool. There was just so many people and so few week-ends that overlap were bound to happen.
Our imperfect and unofficial solution : It's OK to plan at the same date if the events are different types (CQB vs milsim for example) or geographically aimed at the different player pools.
We also created a thread to post the dates of private games so we know they could conflict with our games.
Again, imperfect but it works for us!