assigning to an opponent one's own faults is a common form of attack. it's called projection. I suspect it's often done unwittingly, simply for applying one's own motivations and forms of reasoning when attempting to formulate a theory of mind to understand and predict the opponent's behaviors.
it's very common behavior, alas. I suppose every conflict involving numerous people will have plenty of people espousing such theories on all sides. it's not cool, but there it is.
seeding hatred often finds fertile minds, alas, whether among one's allies towards an opponent, whether attacking an opponent and bringing hatred from all opponents onto one's allies. but aggressors, invaders and the likes tend to forget their own attacks, and perceive and resent only the "unjustified" reaction brought upon them. that's very human, but also worth talking politely about if we're to overcome conflicts and pursue useful cooperation