The story was never about The Rock. It was always about Roman and the Bloodline. Taker has had issues with Roman in the past, even if it was a while ago. Austin has not.
Every single person who entered to help Cody had some beef with the Bloodline pre-Rock.
Cena with Roman/Solo
Seth with the entire Bloodline
Jey with the Bloodline, especially Jimmy
Undertaker with Roman
Austin showing up made no sense other than for a huge pop. I'm not saying Taker is vital to the story, but him helping made more sense.
The Rock has literally been the main focus of this entire buildup post Mania, he's been the star of the entire show, the one driving the attendance and the ones driving the ratings. The Rock/Cena faceoff? Immediately their rivalry was brought up by the commentators.
Roman & Cody were overshadowed by The Rock every step of the way from The Rumble on.
Taker has no history with this version of Roman, again, he literally lost to the face version of Roman, zero to do with the Tribal Chief, the bloodline we see today 7 years later.
Cena? Makes some sense, he's had battles with The Rock & The Bloodline, though getting humiliated by Solo the jobber certainly hurt that as well.
Having Austin come out to confront his biggest rival at the biggest show in which they have the most history? Makes some sense, particularly given he's Hollywood Rock again for the first time since Austin was retired by the same character.
Taker? Zero history with the Tribal Chief, zero history with the bloodline, lost a match to a face Roman Reigns 7 years ago, clean. To my memory, I don't remember a rivaly of remote significance with The Rock either. How about his history with Cody? Non-existent. Mark sat around on his ass for 7 years, watched Roman completely switch characters while creating a new faction and screwing over pro wrestler after pro wrestler many of which he had significant history with...only to suddenly decide now in 2024 that he's "had enough" and is going to stick his nose into the Main Event? I'm not asking for much here, but just a small modicum amount of logic really does go the distance...this lacks even that.
The point is if you're going to create a mess for the sake of a cheap pop and insult the intelligence of your audience, bring in the bigger fish.
Maybe I've just gotten too old for todays product, I'm sure if I was 10 years old I would have eaten it up.