Most game controllers today are wireless. On the other hand, keyboards and mice are still not completely free of wires. It's not a problem if you only play on the monitor, but if you have a wired mouse/keyboard and switch to a TV where you play with the controller, the hassle is when you need to change the game. Steam Big Picture mode has support for controller management, but not all games are on Steam. And then you need to go back to the keyboard and mouse because the controller does not have the full functionality of switching between games.
That scenario will soon change as Microsoft introduces new functionality to Windows - the Xbox Controller Bar. It is a small menu with six entries - three most commonly run games and three launchers - which is obtained by pressing the central Xbox button or a similar button on other controllers. In this way, PC games and launchers can be launched using the controller itself, ie. without a keyboard and mouse.
Currently, this is in testing, and there is one rule that sets the whole thing apart from a similar system on consoles. Namely, the Controller bar can only be used while the player has not started the game. In case his game is running, pressing the specified button will still get the classic Xbox Game Bar as well as pressing Windows + G.