Why do kills/damage not count from holiday event?
This is more so a question for EA/Respawn, so let me just lay out the reasoning as to why it should count...
These themed events are a nice change of pace to the regular game modes, and offer so much needed variety to a game lacking in diversity of play options. And as a developer, I am sure that you are creating these events in part because you want the players to actually play these modes.
The problem is that there are a lot of people, like me, who don't play these events simply because playing them doesn't help them grow their stats, which is the only thing to tangibly work on/towards to show your prowess in Apex. I am actually enjoying this holiday game mode quite a bit, but I don't play it because it almost feels like a waste of time since it doesn't increase any of my stats like kills/damage/wins/etc.
I know that there are going to be people who agree and disagree with me on this, but I hope this is something you consider changing in the future.