Countless computer scientists and cognitive scientists will tell you you're wrong. Full stop. This is a fact, not an opinion.
Fitts's Law states that the time and difficulty of rapidly acquiring and interacting with a target increase as the distance to the target increases and the size of the target decreases.
It's much easier and faster to press a fixed-size, stationary key on your keyboard, provided you have mapped your keys appropriately so that, e.g., the Target Nearest Enemy keybind is something close to home position like [G]; and even if there are several enemies on the screen, one can tab cycle through them faster than they could click as long as you have your camera pointed the right way to exclude distant targets. It is actually unusual for mouse targeting to be faster than keyboard targeting, and combat is playable entirely without a mouse if you're a tank or DD.
Mouse targeting may be faster if you're trying to acquire a specific target in a cluster of enemies by clicking an enemy frame in the enemy list when there are about eight enemies to select from, but to say that mouse targeting is "ALWAYS faster. Full stop." is just wrong.