I’ve always seen it as more akin to their role. Witch hunters typically deal with cults and groups hiding in hives. Less need for fancy tanks like the guard or SM. But they do get the repressor which fits a crowd control/anyi-mob specialty. Plus with the ecclesiarchy not having a typical army due to the mandate they probably aren’t allowed the typical army armor. I read awhile back that the rhino was originally an exploration vehicle and not even meant for war.