Yes bounties matter if you have fought. 99% of the time, bounties are spot on determining power level, unless they had the bounty locked. Of course when you compare the bounties the Straw Hats have against their opponents, they beat the higher bounties. The fact that 250 million to 400 million took him about 10 years isn't evidence to you? Idk anybody to be that active, rise to that high of a number, to just go and end up 3x stronger over the course of like 1-3 years. I mean, Jinbei has been in how many battles? What does he have to master that he hasn't already got as good at as he could at? Most of the increase to Jinbei's bounty to come is strength he just hasn't had to show to the world yet. In 1 month of 3 key battles, Luffy got 2x stronger because his peak is pirate king. Zoro and Sanji still have a distance to go with battle strategy and haki, and the minute they get a big key fight in Wano, they should grow incredibly in strength. That's how Zoro ends up at Yonko level, and maybe Sanji too.
No telling how many battles Jinbei has had, and here he is after 12-25 years, and only a little past 400 million right now. With what we've seen from Jinbei in Whole Cake, he should be a little over 500, not 400. But then again, we've not seen Sanji or Zoro fight a real full fight challenge since time skip either. Jinbei fought Ace for DAYS. That alone is a huge resume of experience fighting. With Zoro fighting people like Jack in Wano (not saying that has to be his fight, or that he would win), the Zoro vs Jinbei debate dies. Then consider how much stronger Zoro grows from those opponents.
Now think about Sanji, who has always been a little behind Zoro. Only reason he is about 150 million over him right now is because he fought Pica while they didn't know what Sanji was doing. We know Jinbei won't be around at first, so that means Sanji gets to fight a bigger opponent. With fighting them comes that giant powerup. If he could actually fight Daifuku instead of run, win or lose, no telling how much he would grow, but it would be by a lot. So if Sanji, who has always been right behind Zoro, grows as fast as Zoro (who is at 320, about to be at least 2x higher after Wano), there is no way Jinbei shows up to Wano without only being a fragment stronger than Sanji, at most. If Jinbei is a fragment stronger than a 21 year old Sanji with 3 years of experience, NO WAY he is stronger than a Sanji endgame.
The minute Sanji is pushed to his limits and forced to use up every bit of haki, those legs will become unbelievably strong. For reference, the strongest legs belong to Sai (maybe?), whose kick can one day, or already can destroy an entire island. When Sanji's legs/armament haki reach that level, to the point where he can do that without that families technique being passed down, what can fishman karate do against that? And of course Sanji is already the 2nd fastest Straw Hat, only behind Brooks, who might only be 1st as a gag to his speed on water. I'm not saying endgame Jinbei isn't stupid strong, but it doesn't make sense for him to all of a sudden grow fast after so many years of experience and fights brought him this far.
Also would reference you to this https://www.reddit.c...fthand_men_sbs/ even though I understand if you don't care for it because the french version isn't on the internet.
Idk if it will happen, but I hope Luffy names some commanders. Jinbei, Zoro, and Sanji. Ranking will sort itself out with time, but it would just make the group seem more Yonko-ish.