>>34261734I hear people say that USUM should've been a single game but that would mean a complete rewrite of the SM story, which is something third versions just don't do no matter how much we wish it wasn't.
Groudon and Kyogre's climax was easy to rewrite for Emerald because all you had to do was have them start fighting one another rather than just standing around.
Dialga and Palkia were inconsequential differences in DP and didnt affect Platinum's changes at all
Solgaleo and Lunala are sort of integral to staying in their own versions because theres only one Nebby and Necrozma's whole schtick is absorbing one of the two final evolutions, which wouldn't have really worked in a single third version. I think what probably happened was they realized they had written themselves into a corner and at some point decided to split the third version into two rather than start the story from the ground up, considering most of the senior staff was already working on the Switch game at that point.