Explain this to me, mouse clicking vs keybinds

So, I'm back to playing WOW after being away for over 20 years. I stopped playing Vanilla in late 2005 or early 2026.After dropping WOW I had a brief stint playing EQ2 until early 2007. While playing EQ2, I was able to break my habit of mouse clicking abilities thanks to my trusty Logitech G13.

However, now nearly 20 years later, I am back to mouse clicking. I want to get better at using a keyboard (and still have that G13 to help), but I also go to thinking... Using the keyboard is generally considered better as it allows you to go through your rotation faster, right? Well, what if I move my mouse between abilities in my rotation before GCD ends? That should be just as fast, right? GCD sets the lower limit on the amount of time between activating abilities, so what difference does it make if I'm using a mouse or keyboard, assuming I can still move faster than GCD?

I need to get to a training dummy and really get some objective results for myself, and ultimately just play how I'm most comfortable, but I'm wondering what people's thoughts are.