Makes sense to me since they already announced 3 WoW expansions which will still be releasing near next Blizzcon and likely not far enough to announce the next one, Diablo IV's expansion was already announced and the closest project to reveal was cancelled so they likely have nothing new + major to announce for 2024 and D4's expansion + WoW expansions will just be thrown into the June showcase or Gamescom.
I know it's an event for fans to gather too but these events are expensive as hell to hold and a reason why everyone is moving away from physical in person events because renting out massive venues for thousands of people is expensive as hell compared to throwing up a digital stream and there's no point doing a digital showcase just to say "look some more at expansions we already announced" instead of shoving them in an Xbox event.
2023 was largely held up by WoW and when Blizzard has barely anything to announce they get ripped apart by online community even if the event is for fans too. Blizzcon has also been cancelled 4 times in the past as well so I assume it will be back for 2025.
