Already went over this
He certainly could against Sukuna. He even calls out the fact that most of the attacks he took inside Yuta's domain
would have been lethal without RCT. Yuji can naturally convert his CE to blood, reattach limbs and overall is much more capable when using RCT due to his physiology. If an attack doesn't destroy his head it simply won't kill him
He was outskilling Todo for most of that fight, Todo just helped him improve his CE control
He lost because Choso surprised him with the blood armor and then one shot him. In terms of raw skill Yuji was superior
Mahito was spamming big moves and shapeshifting but any time they fought with straight hands Yuji mopped him
Yes a massively powered up Mahito was gonna do that, no amount of skill is gonna save you when your opponent can Senator Armstrong through all your attacks
And I'm talking about end of Shinjuku Yuji, i think I made that pretty clear with all the times I brought up Shrine or his DE
Sukuna has the highest CE output in the verse (or is tied with Gojo) and even while nerfed from UV he was dealing one shot level damage to Yuta and Yuji, so while the drop in output may not seem that significant, it is when you consider who Yuji is up against. Against sorcerers with much lower outputs than Sukuna the drop is gonna be much more obvious
Same thing with their control over their bodies weakening. Sukuna had specifically taken measures to insure Megumi could never break free from his control so his grip on his body is gonna be far greater than any other reincarnated players
Yuta, Helicopter guy, Higuruma, 16F Meguna. Idk where you saw the 7 fights his been in since Mahito. Against Yuta he was actively holding back and wanting to die, against Higuruma he didn't have CE to use BF with and he one shot the Helicopter guy anyway.
He hit his first ever BF on Hanami with no outside help or experience using it before and did so as Hanami was attacking him. The reason he's always had outside help when performing BF is because Yuji has outside help in most of his fights anyway but that doesn't mean he can't use it on his own. Especially when it's mentioned several times that he extremely lucky with the move, to the point where Mahito new he'd be shredded if he didn't take it into account while fighting him solo.
I think it's a lot more disingenuous to act like the technique that's basically Yuji's main move somehow is a non factor in his match ups.
In conclusion...