Jack of all trades, but master of none
Controllers are designed for versatility and approachability. Consider that the same controller is intended to simply work across all genres: it’ll work whether you’re playing first-person shooter, racing, fighting, or other games.
Serious gamers know that more specialized hardware exists. They deliberately build their gaming setups around their interests, often sinking real money into controller mods and higher-end controllers.
FPS? Mouse.
Racing? Wheel and pedals.
Fighting? Arcade-style fighting sticks.
Just as no serious flight simulator enthusiast plays with a keyboard and mouse, no serious FPS enthusiast should play with a controller. More of them should be casting their gaze towards the familiar mouse.