This is done mostly because I want to mantain the “soft reboot” that unlinks the Epilogue to Atop the Fourth Wall, something that I feel I can’t do if I integrate Season 2 of “Better Together” in the Epilogue.
Also: the reason the Event Synthetizer (the machine Sci-Twi built to bring people to other universes into the Ponyverse, and the one that allows residents of the Ponyverse to travel to other universes) only works for an hour is tied into something established in “Spider-Man: Into the Spider-Verse”: people from one universe can’t stay for a prolongued time in another universe, or else their molecules will explode and they will die. This effect varies from person to person and from universe to universe, so Sci-Twi decided to play it safe by having the effects of the Event Synthetizer only last an hour, since everybody can survive at least an hour in a parallel universe.