MCH relies on a lot of things lining up just right in order to stack and maximise potency buffs.
You have ammo, heat, hypercharge and wildfire to keep track of and you want them all at the same time for high burst damage.
Besides that, you rely on your turrets to bolster your autoattack, which increases your overall damage output, even if it doesnt seem obvious.

Its definitely a tricky job to master and until you do, its underwhelming.
But if you ever wanna try out PvP, you'll absolutely love it.