Custom loadouts change everything about the MP. It changes the weapon sandbox, the in-game combat, sometimes even the maps to accommodate for possible Armor Ability user choices like Jet Pack. CoD was the first to incorporate many of these ideas, maybe not every last one, but a good number. Other FPS games followed suite, but they weren't nearly as popular as Halo was, which used to be the #1 console shooter. It didn't need any of this shit, and now it all ruined what used to be there: a unique, arena-based experience.