Carrot’s going to say goodbye to the Strawhats during the Wano epilogue to help Momo or return to Zou with Wanda, and we’ll be halfway through Elbaf with her supporters still clamoring that she’s going to appear at a clutch moment with a full epiphany about Pedro’s will and join after Elbaf. Because Jinbe set a precedent, don’t you know? Denial is going to run the whole series.
Jinbe is completely different from the other recruits. One nakama’s extraneous circumstances does not mean there’s a new pattern for NW recruits. Jinbe was intrinsically tied to two emperors and had a pirate’s honor to abide by that prevented his joining. Carrot has none of that. Nothing that needs to be settled before joining. Carrot should have joined in Zou if she was going to at all. No one doubted Jinbe was a nakama after Fishman Island when Luffy asked him to join. He was integral to FI, to WCI, and now to Wano. Carrot only had one scene to help the Sunny flee.
The Minks are sworn allies to the Kozuki. All the minks are going to support Momo as the new shogun, Carrot included. Carrot’s getting some closure now to complete her role in the story and will realize the Dawn when Momo does. If Momo is the key to the Dawn, and he’s not going to travel with the crew, then there’s no reason for Carrot to do so either.
As for Yamato, to say it isn’t his arc is being a little obtuse. He wouldn’t have made sense as a character before we knew who Oden was. As soon as the setting shifted to Onigashima, Yamato was immediately in the action and has been prominent ever since. Onigashima by itself will be longer than most arcs where a new character joins, so Yamato was never absent when it mattered the most.
Carrot's fight isn't in the plot yet, and there's a very real possibility that it will be offscreened and Oda will just let the anime handle it like so many other Wano fights. I think that it will have payoff, but I don't think that payoff will be named nakama. Every time a character joined, the character had to fail for Luffy to come in and beat the big baddie. Zoro was captured, Nami was utterly defeated and outwitted, Sanji was beaten down, even Jinbe didn't want to confront Hodi. Is Carrot going to fail and then Luffy comes in to beat Perospero? If we want to set up a pattern for new nakama, the recruit needs to feel indebted to Luffy in particular, and that's just not happening for Carrot.
I see this said about people who think Carrot is going to join all the time, but I never see anyone who thinks Carrot is going to join actually say this. Pretty much everyone has agreed that if Carrot doesn't sail away with them at the end of Wano, she isn't joining.
I just don't see the same disrespect being shown toward people who believe Yamato is going to join.