Zeus not fighting in the Titanomachy would be a massive change to Greek Mythology.
We know that's at least 10 years of front line experience there given his thunder and lightning were repeatedly said to be weapons he wielded against the Titans. He even slayed Campe as a young man, the Warden of Tarterus in order to free the Hekatonkeries, which is a being who is no joke itself.
And then Zeus not overcoming the Gigantes and Gaia's anger at the Olympians in the Gigantomachy would be a great change.
Moreover we know that the Gods attempting to overthrow Zeus, especially Hera, Poseidon, and Athena is a big part of his mythos. And Zeus won there too.
Finally one of the ultimate trials he overcame and reasons he stood as King was in his defeat of Typhon, a monster said to be beyond basically all of the other Gods and capable of withstanding all but Zeus.
It was essentially said that without Zeus taking the rapid action he did, Typhon would have ended up ruling over all the gods and mortals in Greek myth.
I mean, I get it, Zeus has a lot of shitty traits.
But to deny that he does have his areas of competence and that he does hold power, skill, and experience is to do the character and underlying mythology a vast disservice and would be pretty overt and heavy handed flanderization.