Performance differences are the product of both knowledge gaps and technical skill gaps. If you want performance to actually reflect player technical skill, you need to simplify the former and add depth to the latter, which is the opposite of what this game has done historically. Turn off tank stance and turn on Cleric Stance. Use STR accessories over VIT. Strafe lock your target to land directional autos. Established players love these sorts of differentiators because you exclude a portion of the playerbase from being competitive purely on knowledge alone. But you're not measuring player skill.

Many other game genres outside of MMOs are weighted in the exact opposite direction. Having map knowledge in an FPS game will give you a competitive edge to a certain extent, but a complete novice with superior aim can still outclass you on raw mechanical skill alone. As they should, because that's the entire point of the genre. Ideally, players should have a relative clear picture on how to excel without having to do a lot of additional research (i.e. stay on the boss as melee, keep casting as ranged), with precision movement actions and bullet hell tier dodging being the primary determinant of their uptime. The rotational mechanics are entirely fluff (you're going to memorize the GCD by GCD play by the time you're done prog anyways), and how hard you get pushed is very much dependent on fight design. If you want to build up the technical difficulty of jobs, then what we really need to see are more complex movement and evasion actions and fights that force you to use them to their full potential. That's why MOBAs can get away with five buttons, of which one or two might be entirely dedicated to movement.