Good point, guess I didn't think of that; but then again, maybe it could be configured so that when there is poor visibility, someone can disable the effects without improving their own visibility. For example, the enabled weather effects only permit visibility 1,000 yards out, but someone who has disabled the weather effects would be able to see a clear blue sky but not another aircraft until they are 1,000 yards away. Until the aircraft is 1,000 yards away it would simply be invisible so no one has an unfair advantage.
It’s just a thought.