I genuinely don't get the correlation between questioning about dragging jinbe's official join and the only possible additional crew is limited to 1 person._. How can it conclude to "there's no way there'll be 2 more new crews because jinbe yada yada yada" ?
I believe Oda does intend to have more than one person join this time. However, three people at once feels like too much when it's always only been one at a time. Oda had a chance to let Jinbe officially join in WCI, which would have given both Carrot and Yamato more than 100 chapters to develop in Wano without his absence hanging over everything. That would have spread things out more evenly and would still allow for breaking the precedent of just one person joining at a time.
However, Jinbe made it official in Wano. This is the arc he will get his toast and leave with the crew on the Sunny. Having another person joining next to him already feels like it'll push into his accomplishment, but it can work if there's a reason for it, namely if it's the 10th and final person before the crew is complete. If it's just so Oda can cram three or more crewmates in as quickly as possible when he didn't even have to, that doesn't make sense to me.