The most popular combat addon is probably ACT and that is purely for cutting down on the time it would take for you to look at FFlogs and do the math by just calculating dps for you so you know when you performed below the expected standard.
If you're gonna call that cheating then I guess talking in voice chat is also cheating, because you can communicate outside pulls and explain strats between them easier. Pretty bad logic if you ask me. Do console players not use voice chat?