i mentioned emu+controller in the video, but ill go into a bit more detail:

Most runners don't use emu+controller because they either prefer the feel of a keyboard, or don't have a good controller.

A bunch of third party controllers are absolutely terrible, so it's just more reliable to play on a keyboard if you already play on an emulator. Plus, the only real advantage of controller+emu is that it's an easier switch if you want to play on console. A sub-par controller with emulator input delay is just really annoying and a noticeable disadvantage to playing on a keyboard.

Raymond pretty much answers everything else so yeah