Sorry, but to me that just seems ridiculous. You want to devalue something that someone took the time to obtain legitimately just because you were busy during the event? This is how trading on Smogon works. If you're not able to obtain something yourself, but someone else is, then you trade things that you have that they want for it. For example, User A RNG'd a shiny Kyogre in Heart Gold. User B doesn't have Heart Gold, but wants a shiny Kyogre. User B then has to trade things that User A wants for it. The same situation occurs with events: User A has a Genesect. User B can't get the Genesect because the event has passed. User B then has to trade things that User A wants for it.
I'm not sure why you think that because something is rare, you shouldn't be expected to trade a lot for it. That's counter-intuitive. Rare things are rare, so they demand a higher trade value. If you miss an event, but don't want to trade a lot of stuff for it...then I'm sorry? Using an injected wondercard to take the rarity aspect out of the equation hardly seems like the answer to me. It's almost like Syndrome's argument in The Incredibles: "If everyone is super, no one will be." In this case, if you inject a rare event, then you're hurting the trading value of those who took the time and energy to acquire something rare for their collection.
All that being said, I realize that injected wondercards are allowed in this forum if they're specified. I'm not saying they shouldn't be allowed. I'm providing an explanation to Jezabel Wrote's question of why some people don't like injected wondercards. If anyone wants to have a conversation about this, I'd love to talk more on my profile.
