1) Like you already mentioned: The segmented crew plot happened in almost every arc. It happened in Skypiea, it happened in Thriller Barc etc.
2) The difference this time is that we didn't see the full SH crew united for almost 7 years (2013-2020). On top of that we had stretches of 2+ years, where one half of the SHs didn't appear at all.
That's not a new idea, it's just another old idea taken to the extreme ... and not in a good way for many readers.
Other mangas can work around the problem, but in OP the interaction of the SH crew is one of the central themes in the story. Oda basically shot himself in the foot with the decision to split them up for so long.
you're saying "it's the same thing but different." Each Straw Hat was present for Skypiea, Thriller Bark, etc. You should be saying like, Baratie (from over 20 years ago). Unless you directly mean that they weren't actually literally together throughout the arc... why would they be, what the hell kinda storytelling is that?
The Straw Hats were split for two years, and then together for roughly two years before spending 4.5 years apart. Being literally together isn't the narrative, it's a visual created to express the narrative. Oda either uses it to signify unity or the approaching climax... except when he doesn't. Thriller Bark omitted Luffy from the group, Sabaody used it to visualize their complete defeat instead of victory, a whole two years went by with no SH showcase, and we had the return to Sabaody and the Straw Hats in FI standing together to show their actual return as a group. After Punk Hazard was the arc where they actually split. Yes it is an exaggerated version of again stories like Baratie, but repetitive doesn't mean "something that's happened before." In 25 years of one story, surprise, a lot of things will occasionally reoccur, but repetitive implies consistency.
Again, it's a weird idea that Oda is repetitive but shoots himself in the foot because he goes long stretches without doing that thing (focusing on the central theme of crew interaction). We get long term guest stars like Law and short term guest stars like Pedro. We get intermittent guest stars like Raizo and consecutive guest stars like Carrot, and the last nine years have built up to this major arc with the whole ensemble. Oda does things familiar to the story and relatively new things. Like yes we had Vivi, Johnny, and Yosaku for those same ideas but you really have to dig deep into the series, maybe binge read like 60 volumes in a row, for them to make this feel redundant.
That kinda gets me to your others complaints. Like how a story about sailing to islands always starts with them sailing to islands. They've flown, come up from the oceans depths to one, found one on top of a giant elephant, had one fall on them, what else? The idea is that adventure can happen anywhere, out of thin air like Jaya or in the middle of another adventure like Law showing up.
Locals? Who was local in Punk Hazard? Is there not a different resolution between the citizens of Yuba and those kids, or the samurai they found there?
Lose the first round, that very vaguely fits Sabaody to FI to PH to Dressrosa. Luffy, the main protagonist lost once in those four arcs.
"SHs go into round two against the villains (main fights) and win, saving everyone in the process" People were actually upset that this didn't happen at all in WCI.
And so on. These are thoughts I've had at work since you posted so it probably comes out as rambling but I think you get what I'm saying.