Let's get straight to the points. Here's why.

1. All Roman Reigns's matches would feel less predictable. Let's face it; the fact that Reigns is still holding that championship actually harms both that title (which has NOT been defended in THREE months as of this writing) and the matches in which Reigns is. If you think Jey Uso has any chance of beating Reigns at SummerSlam 2023 (assuming that match does happen in that PLE), let's face it: he won't because the way things are going now, Reigns is holding on to that title until Cody Rhodes finally beats him at WrestleMania 40 (it should have been WrestleMania 39, but whatever). But if it was a purely grudge match, and there's a lot of grudge in that? Jey Uso actually has a better realistic chance of winning that potentially career-defining match. And maybe he still gets a World Title match anyway because of that win.

2. Literally all the major beats of the current chapter of the story would still be the same. Had Reigns lost to Rhodes (and he should have), it would justify him being away for a few weeks. Heyman would dismiss the loss as a fluke (because of all the interference that did happen in that match). Once Rhodes decides to only hold the WWE Championship and vacate the Universal Title, that's when Reigns comes back and puts himself into the Universal Title tournament (taking place like how the World Heavyweight Championship tournament happened). He could even politick his way into being automatically in the finals at Night of Champions, where Rollins FINALLY gets his revenge for Reigns DQ'ing himself in the 2022 Royal Rumble title match. Then Reigns tries to win the Undisputed Tag Team Championships with Solo Sikoa on a SmackDown episode, but fails. He then tries to bully his way into MITB, but it also backfires (thanks to a botched interference from one or both the Usos). Then Reigns starts blaming the twins, and instead of the smug gaslighter, we get a more unhinged version of Reigns. We get the Civil War match to open MITB, and The Usos win. Jey Uso pinning Reigns did not need the "first time Reigns gets pinned in three years" honor because there will be intrigue regardless and The Usos will still be viewed as underdogs compared to Reigns and Sikoa.

Now, onto how it would have affected Cody Rhodes:

1. Cody Rhodes (who would be exclusive to SmackDown) would still enter into a program with Brock Lesnar, and beat him both times. If you're complaining that Rhodes has not overcome enough adversity by this point, you're wrong (Stardust, being released, and that torn freakin' pectoral muscle say hello). But to use that argument anyway, Rhodes doesn't need to even have that long of a title run to establish himself because he would still be as over as he is now. By beating Reigns, he finished his story, so he's on to a new one. With Rollins being the Universal Champion and Rhodes with the WWE Title, you can have both try to subtly one-up one another or something like that. You can then have him lose the title by a MITB cash-in (and put someone over and elevate them to the next level), and have him go through adversity to the same degree he is supposedly going through now. You rebuild him in time for WrestleMania season, and have him either beat Reigns in a rematch (yes, Reigns in this timeline would realistically be champion sooner than later again) or put over someone like GUNTHER (who, with Imperium, can go to SmackDown and SHOULD win the 2024 Royal Rumble; Rhodes would have regained the title by this point). Speaking of which ...

2. GUNTHER should win the next Royal Rumble. In the current timeline, it is likely that GUNTHER and Rhodes will be the final two again (because Rhodes needs to finish the story), so as revenge for the previous year, GUNTHER eliminates Rhodes this time. But can you imagine if instead of Rhodes, it would be Roman Reigns that he eliminates last? Yes, Reigns would still feel like a bigger elimination than Rhodes would be (because of that still impressive less-than-1000-day run in this alternate timeline; that 1000 number is, in the grand scheme of things, ultimately meaningless because it's still Roman Reigns with the longest title run of the modern era). That would be a huge boost of GUNTHER's credibility, on his way to a World Title win in the main event of WrestleMania 40: Night One or Two.

In short, the major beats of the storylines we're seeing now (the fall of the Bloodline, Rhodes vs. Lesnar, Rollins as RAW's top champion) would still be the same as they are now, except it leads to less predictable matches, avoids the unnecessary creation of ANOTHER World Title, and sets up more performers like Jey Uso and GUNTHER to be elevated even more because Reigns, Rhodes, and even Rollins will ALWAYS be over with the fans and have unbreakable credibility.

Instead, we are stuck with LOLReignsWins, except he's a heel that is basically Brock Lesnar who does NOT defend the most prestigious championship in the industry as much as he should. I rest my case.