I will not fault a single person for thinking a reveal was going to happen at the VGAs since logically everything lined up. Character 5 has to come before March, there's been at minimum of about 2 months between reveal and showcase, it's a big gaming event, its 6 months from E3 which is a great time of pace for updates or game announcements or acting like a follow-up to E3, it just passed 1 year since Ultimate's release, Nintendo told people to tune it and the biggest reason: there is already established presendance of a reveal at that VGAs with Joker.
So thinking a reveal was coming is actually perfectly reasonable concerning the situation. Not a guarantee of course, but far more understanding and realistic than thinking something Smash was coming from the Nindie's showcase earlier.
That said, the VGAs were dull and pointless this year. Best fighting game was pushed to the preshow, the actual awards came off as they thought they were padding themselves, Game of Year had no pomp, Nintendo's contribution was nonexistant despite tweeting the event, and two next gen consoles were announced and were not earth shattering reveals as they SHOULD be.
That image of the audience member asleep sums it up.