I'm still confused as to why they thought it'd be too complicated for kids. Literally the most complicated thing about it would be knowing to go to Mount Coronet and then catching Arceus. Otherwise it's just: get flute from event, go to Spear Pillar, go up the steps, and catch Arceus. Unless they only programmed the ending of the event into the game, I'm not sure what was so hard for kids to understand.Well, it is to be known that Arceus is indeed a Mythical. Therefore it has always been event based.
If you remember the original Diamond an Pearl games Arceus was only accessible only by Action Reply aka cheating only because #Blame Game Freak for thinking it was to hard to understand to kids back then so the event never officially happend.
So with the new Switch versions an legend of Arceus coming next year game freak probly now realizing it was not complex for kid/adult gamers to figure the cancled event