If there's anything akin to a cardinal sin among certain sections of the PC gaming community, certainly in World of Warcraft, it's being a "clicker" (see definition 3) - someone who clicks their abilities on screen rather than have everything mapped to keybindings.
And heaven help you if you're a "keyboard turner" - someone who uses keys to turn your character instead of the mouse.
All things being equal, keybindings for abilities and using the mouse to turn your character and in-game camera are more efficient. But not everything is equal. Disabilities and learning difficulties can have a massive impact on the way you play. After a period of illness in her late teens/early twenties my wife was left with grip and dexterity issues in her left hand, for example and still has issues to this day.
I used to virtually live in video game arcades when I was a kid. I was good at the games, very good, to the point that the arcade owners would ask me to play new games to see if they would make enough money. If I could finish a game within the first two or three days of it being installed they probably wouldn't keep it. Some games had variable difficulty settings (who remembers dip switches) and I was regularly called upon to test changes to see if they made it hard enough.
In those days things were a lot simpler. I had excellent coordination and fast reactions but the controls were relatively minimal: a joystick and a few buttons at most.
For whatever reason I struggle with anything beyond that; I don't know if it's just because I'm older or that there's more controls involved. My mind refuses to deal with so many things and doesn't seem to send the right commands to my hands. I am unable to use an Xbox controller for the same reason meaning most console gaming is out for me as there is no alternative input method.
I'm probably about a 50/50 keybinds/clicker person - maybe more like 40/60 - and would likely get ridiculed for that from elitest players. I'll use the keyboard where I can but have to back it up - a lot - with the mouse. It takes me a long time to get used to a layout and I don't handle change particularly well. Call it muscle memory, or just familiarity or practice, but even though I know where things are that still doesn't always translate to being able to use them depending on what else is going on.
Times like this, when the game and your abilities change and you have to relearn things or move things around, are particularly difficult. It may seem melodramatic but the changes this time around mean that I can't play how I was going to over the next WoW expansion. Things have changed too much and I haven't got the mental capacity/physical dexterity to cope with it and remain a viable player.