Its also nonsense to not explain fully you're point of view.
1) Zoro´s feats have shown him already being above mid tier, which is reserved for people around veterans or Vice Admirals. He protected himself against a top tier well enough, while even high tiers can toy around with mid tiers (DD vs a lot of them, Hancock, Sabo and so on), and beat an opponent who took the entire country hostage and who nobody could to something against except Law, Luffy, Fujitora and DD himself on the island (even Sabo is questionable), which made a legendary pirate and a lot of mid tier look at it in awe and praise him, and it took only that long because Pica was constantly running away from the fight.
Zoro then got a chance to powerup and train with a sword that puts stimulates growth.
For him to be now where Luffy started after the TS (he did not grow against DD and Cracker btw, it´s a logical fallacy to assume each battle will make them improve) is not too far-fetched.
2) Sanji came out significantly weaker than the other two, but he was still in the upper mid tier spectrum, could tussle with Vergo, could fight Daifuku equally, and can blitz guys like Oven, while using his strongest move post-TS only once.
And now he has received a powerup which is literally a booster of his stats coupled with a seemingly overwhelmingly ability like invisibility, and he dominated the few panels against P1 while only trying out the suit and not being used to it, which, in the manner he did it, suggests a high tier spectrum.
Putting these guys into high tier fights and making them grow as Luffy did against Katakuri is pretty accurate and appropriate.