Wrestlemania 2000 main event/backlash question

After your reading your rant on the Wrestlemania 2000 main event and rewatching backlash with Rock going over HHH finally, why in their right minds didn’t they just do that at Wrestlemania? You had the overbooked smoz, Austin’s big return, wouldn’t that have been a much better ending to Wrestlemania? 

I think Austin was literally only able to do the run in that he did by Backlash, and even then he was barely able to walk out there and was still months away from returning.  Wrestlemania would have been too soon, so it all worked out in the end.