the existence of these dark matter free galaxies can be considered proof of the existence of dark matter, the existence of these dark matter free galaxies can be due to the fact that when normal matter collide, they experience friction and cause a more splashy collision, while dark matter just passes next to its opposing collider, so, when 2 galaxies collide head on, the normal matter splashes while the dark matter just continues on its path, the normal matter reforms smaller galaxies, however this time lacking from any dark matter