Man the discussion is pretty much dead huh?
You know its bad when the Yamato won't join and Carrot will join arguments are now solely reduced to things outside the manga. Things like Oden's journal and who's better suited to fight a BB pirate are pretty empty arguments that have no real weight to them.
Yamato having read Oden's journal doesn't mean spit. There was a possibility before of Yamato spoiling something to Luffy, but she already returned the journal to Momo, pretty much signifying that the journal's role had ended and it was nothing but smoke and mirrors. That argument is already dead. The journal's sole purpose was for Momo to understand why he can't die just yet (something that Oda himself still hasn't bothered to reveal and explain it himself), it has nothing to do with Yamato. With the journal returned, Luffy can't even rip the journal apart in front of Yamato to voice his displeasure of Yamato joining. The tool just isn't there for this scenario to play out anymore. And don't tell me that Yamato is gonna tell Luffy that he read Oden's journal and then Luffy won't allow her to join the crew- that already happened in the attic and Luffy never said no. There is no point in having Luffy say no now, its too late now and we're already well beyond that point, story telling wise it achieves absolutely nothing.
Carrot being more suited to fight a BB Pirate (whoever it may be), is also a weak argument that has never gotten more credible as the Wano Arc has progressed. Carrot couldn't even beat Perospero in a tag team who wasn't even a beast pirate. If she couldn't even do that what's the argument that she's strong enough to fight a titanic captain? Yamato meanwhile blitzed Ulti and can clash with Kaido. Every single straw hat in the Wano arc thus far have feats or have won in a fight from a prominent beast pirate, be it a topi roppo, a calamity or Kaido himself. This also includes Yamato-having fought not one but two prominent beast pirates-Ulti and Kaido himself, making her tied with the Monster Trio (Luffy fought Ulti and Kaido, Zoro fought King and Kaido, Sanji fought Queen and Page One). Yet Carrot is the only one left who hasn't fought anyone important from the beast pirates. If Carrot is the next straw hat why isn't she contributing anything important to Luffy and the Straw Hat crew's victory over Kaido and the Beast Pirates like a Straw Hat should? The Beast Pirates are the most powerful enemies the Straw Hats have ever faced and their defeat will also be the crew's most important victory thus far in the entire story, but Carrot isn't a part of it?? Carrot has been so insignificant in the Wano Arc that she most likely can't even attract CP0's attention to get a bounty. That's not a good sign for a Straw Hat joining the crew post time skip and this late into the story. I can't imagine Carrot going up against a BB Pirate (whoever it may be), and he or she not even knowing who Carrot is, that would be embarrassing to say the least.
Arguments like these are all just speculative and are as credible as Sanji vs Katakuri or Sanji vs King. You can give as many reasons as you like in these kind of arguments, but at the end of the day at most its all just wishful thinking because there just isn't good precedent and reason for it to happen in the manga. The necessary buildup and evidence just isn't there.