there’s a lot of disadvantages in using a controller (and advantages as well). it aint your fault. is the design
however tapping a button with your thumb on a controller is much faster than tapping a key with your index finger on your left hand (supposing you are right handed)
the problem with the controller fire button is that is located in your trigger, and it is more difficult to do it faster
although… there are people who shoot real guns at extremely fast rates. i dunno what the difference would be between a hair trigger and a controller trigger, but I supposed there could be mods that would help you achieve it
I don’t see why would that be a problem. It can be done in a real gun and is perfectly legal and does not ban you from competitions. as a matter of fact, almost everyone in serious shooting competitions use that
then you have controllers with paddles, which are currently being used on esports without any negative feedback