GAC matchups

I think blocking players for a season that signup but dont attack would massively help MM. I've had this a few times but I can't make sense of why a player is doing it unless its for some sandbagging purpose I dont understand. They had to select "join" so they're at least active but they dont get awards unless they attack, correct? Why would a player do that?

I've "beaten" accounts with nearly double my GP because of it and I think that kills me in future matchmaking because I won a match I would had certainly lost if they played.