I have mad respect for people who do all their skills with a keyboard and use shift/control combos. Personally, I mix keyboard and clicking because it's a lot easier for me. For example: There is no way I can hit ctrl+5 with one hand without stretching it in the most inconvenient of ways (small hands, big keyboard issue) so I would have to use two hands to make it work and leave my mouse alone and I'm way too used to using my mouse to adjust the camera angle.. I might completely screw up fights. Just.. no thanks.

I did watch a streamer once. She was doing a raid while mostly clicking and I wasn't entirely sure how she managed to be part of the raid because she was SO slow. Literal "Hovering over the hot bar looking for the skill to click on" type of slow. It was unbearable to watch. It certainly doesn't work for everyone.