I'll ask again, from a story telling perspective what merit is there to Oda restarting these matchups with these two characters?
I think the problem is, you and I have a different assumption as to how the matches "finished". I personally do not believe they are restarting, just simply that Oda decided add abrupt transitions in the midst of their battles. Aka, there are just breaks into their battles, its non sequential.
From a story telling perspective, a few reasons I can give are:
- Sun God Nika has not really been elaborated on
- The anger Jinbe feels about this topic has also not really been touched on, whatever relationship Nika has to the Sun Pirate symbolism
- Who's Who's actual identity has not been revealed. No actual name, just his status to Rob Lucci in CP9. CP-0 purposefully left out his name, why? No face reveal either. Why?
- His direct relation to Bao Huang and the Mary's is unknown, yet they share the same symbols on their bodies. For some reason, CP-0 are using those feeds, not Who's Who.
- People forget that for 1000 chapters, Franky mostly fought with his own body, not General Franky. Franky got out mostly unscathed in his fight with Sasaki. He has far more weapons to his arsenal on his own person than a suit of armor.
- Ancient Zoans have high recovery. With no transitions on their defeat, we can't even see if they are down.
- Who knows if Oda wanted to have them defeated, only to have them recover and/or use Awakening? This is something we can't know for sure until we see them down first.
I actually ask this seriously, try and show me another example in this series where a fight has "ended" and you couldn't see the outcome. These 2 fights would be the first ever in the series that did not clearly show the outcome of a fight. What I mean by this is show the villain laying defeated, or the protagonists acknowledgement of a win, typically with a "don" or "doom" sfx. It happens quite literally every time.
Here's some examples of what I mean out of many:
Now go back and compare to Jinbe and Franky's fights in Wano. They do not receive this. Robin did this chapter, that's what I mean. We get a little "ben" and a closeup shot of Black Maria laying defeated.
That's all I'm trying to say. I get the merit that they "should" be over, but hopefully what I'm saying above makes sense.