User blog comment:Mr.123/Agent Artifact Challenge Three: Bountiful Times/@comment-3270170-20171108012640/@comment-24588058-20171109045926

They probably want to make it so that you can't just have millions of players running around with a million shiny Pokémon (though can you imagine the time and patience to get a shiny Salamence in Sun/Moon? A wild one, not a raised Bagon?). But I'm sure if they put their heads to it, they could come up with a super special reward. Maybe give you a shiny Mythical Pokémon for completing the National Pokédex?