I've been seeing that users have trophies that I don't have (2012 survival, 2016 camp, snowball). Even though I can't remember if I participated (I probably didn't), I did throw 30k snowballs and don't have the trophy awarded.

Did they retire trophies?

Camp Veta was a creative contest in 2016 so that one is retired for sure.

Snowball trophy was Tobias vs Dolly, which happened in 2014, and is also retired.

Oh. I thought there was a trophy for snowballs. I was in school at the time, so I didn't have time to participate in events. I wonder if they'll bring them back

No, they're not - they were one-shot events, so you did miss on them permanently. :(