There should be an equivalent of holdback for skills.
You should be able to nerf your skills to fit certain persona's and the like... Nothing worse than being disguised as Chester McNerd who's never fought in their life, and then suddenly, when targeted by Mixa McBlastman, it's revealed that you're really Chesta McSmash who dodges barrages of bullets on a daily basis. But it shouldn't be something that's easily done. Maybe a certain level of mastery involved in the skill might help, but I think a simple thing like just a basic int and related stat check would be a good idea to enforce people playing to their stats.
I wanted my character to fail a skill check.
I did a full 60% hold back and they still passed the check.
In my mind, someone who is competent enough to do something successfully, should be able to intentionally fail at doing what they otherwise could do.
In its current form, holdback does not facilitate that.