The Game is Balanced to not be Evenly balance, every jobs has a niche and that is the balance.

how we choose to use that is our own right. like the example above, every job in this has had its time to shine in relevant content at some point.

Very rarely does S.E step in and force players hands. one example i can think of is WHM.

Once upon a time, whm wasnt getting the healer role in parties. this is the job niche/purpose/reason its there. so s.e gave it a nice overhaul with JAs like solace for curing, spells like Cure 6 sacrifice and excess to best Cure potecy and casting time.

Pushed RDM to second class healer, not giving them cure 5, however they gave them ALOT of Cure pot. which at the time was unheard of at time.

im sure S.E has a chart with category roles and each job has a priority list. this list is maintained as game Balance. which is why rdm are unique hybrids mages with fastcast and enfeebles, why bst and pup are way better solo jobs, PLD as brick walls, and DD who all differ.

some jobs are easier to excel at then others which translates to player skill and their effort to be above average on their jobs. when players achieve their gear and appropriate game skill level, most jobs are can give each other a run for their money.

however what you asking would literally break the game and the philosophy of the final fantasy franchise.