True. But if iron and gold are added then emerald generators should be somewhere around the lobby too.Emeralds do not give you the best gear.
Considering how Emerald generators aren't in every map. And some simply give you a Knockback mushroom, it's rather not true. Diamond generators are still the main source for the best gear.
I've played quite allot of maps where I didn't use a Emerald generator nor did an opposing team and still I managed to win.