TwoSix
"Diegetics", by L. Ron Gygax
I mean, it CAN mean that, but that sounds more like what I think of as "skill ceiling". But if they're putting Wizards at Average and Bards at Complex, then either they're hilariously bad at actually measuring the skill ceiling, OR they're using a different metric than skill ceiling for what they are calling "Complexity".What makes these classes easy, average or complex is how much mastery it takes to do well. Not whether you can play them in a way that underperforms and have an easier time of it or not.
Based on putting Wizard at Average and Monk at Complex, I feel like they're more taking a measurement of the relative amount of information needing to be processed to create a low-level character and then putting them into play.
Or they're just really bad at measuring these things. That seems quite possible.