From gen 3 to gen 5, Mystery Gift events weren't always just distributions or giveaways. Usually, the item distributed would be an item, like the Aurora Ticket or the Azure Flute, which unlocked a certain area of the region and allowed you to both capture a rare legendary and learn something about its lore. Gen 4 in particular had almost all of its event exclusive legends distributed in this type of in-game event manner rather than plain distributions, which were all we saw in gens 6 and 7. Going to the Pokémon center and receiving a shiny level 100 rayquaza is not nearly as exciting as solving the meteor puzzle to battle and catch Deoxys, journeying all the way to the end of Seabreak Path to battle and catch Shaymin, or talking to people on Liberty Garden to learn Victini's lore.

I accidentally made this thread on /tv/ at first; if a second, identical thread shows up on /vp/, it's because mods moved it.