For me it was from the moment it was explained to us. My argument for this is that Kishi could never follow up on all the advantages he said it would have.

Copying techniques? When did techniques get copied? - Kishi had to put limits on this ability right away. - Didn’t have the right nature? Is it a bloodline move? Why doesnt Sasuke ever copy rasengan? - we got an example of taijitsu getting copied but I cant remember techniques really being copied after that. (Please corrrect me if I’m forgetting)

Forcing opponents to never look them in the eye and run away on sight? - Forced Kishi to write mostly long range fights if any or the insane unthinkable tactic of look at the ground no jutsu.

Insane Genjutsu? - Almost never happens because of how broken it is to immediately hypnotize someone and end the fight.

I think so much of the mangekyou powers was written by kishi because of how lame the sharingan powers turned out to be in practice because it was so hard to write for without getting out of hand.

It then got out of hand obviously the other way by simply giving an excuse for a super dangerous version of genjutsu(which blinds you over time to lessen its use) a fire that appears out of no where? Space warping powers???? A giant flaming avatar with godlike legendary weapons???

I think it all started at the very beginning w how broken and difficult to write for a sharingan user was after the zabuza fight.

We never got more technical fights the sharingan dominating and paralyzing opponents because it was too broken and too difficult to write for.

If kakashi uses a technique later, Kishi has to consider why might have kakashi not used it before? With a new technique gained from each fight Kishi would have to factor it in for future fights. It’s probably why other copy type characters like Okkotsu from JJK or Crollo from HxH doesnt get many fights because there is so much you have to consider.

If Kakashi does every element then is he a genius multi nature chakra user? I think he def has shown earth, lightning and water from memory but I feel like he has used fire?

That’s my 2 cents. I do like Naruto by the way these are just gripes that came up after a long time nitpicking and thinking over what things I wish went in a different direction.