So both night and fog affect the players vision, and both when forced on you and way too frequent just make the gameplay worse.
It is already bad enough that map design no longer lets you have fun by flanking or launching yourself into stupid spots, all that is left is going down gaijins corridor style maps but with fog you can barely even do that.
Does not help when a good 50% of the weather types that can appear in matches is just fog with a different name