Lacking the ability to utilize these keys completely removes the ability for some players with extensive mouse button options from binding in game actions in a way that doesn’t interfere with existing bindings. f13-f24 are incredibly useful in that they don’t show up anywhere on a normal keyboard, and thus, people can use them without worrying about them being bound to other commands. This allows easy binding for things like push to talk or melee without having to rebind default commands from various keys and assigning said keys to say, the mouse.