Sorry, but that's bullshit.
Luffy had already defeated Doflamingo and still would've lost to Cracker, if not for Nami.
Even while winning against both those foes - which were way more powerful than anything Zoro or Sanji have faced so far - he still got absolutely dominated for like 95% of the fight against Katakuri.
Zoro swapped his black blade (!) against one, that has to become a black blade first. Sanji got his raidsuit, that gives him more durability and speed, but we already saw that he didn't even look like he was vastly superior compared to Page One or Drake.
Those "pwerups" are hardly comparable to Luffy gaining future sight or advanced armament haki as powerups btw.
If Zoro and Sanji were able to defeat actual YCs right now, it's objectively just very inconsistent writing, no way to sugarcoat it.
That does not mean that I expect them not to defeat YCs this arc, don't get this wrong. I fully expect Oda to make them beat King/Queen, which I just find lazy though. That was the whole point of my first post.