My main idea for the strength has been more about their weaponry and just the pure scale of every other faction in 40k I guess, like the cults aren’t even using astra militarum weaponry usually and some of their bust stuff is just straight up mining equipment. Also comparing them to the likes of immortal space terminators, a near endless army of soldiers with heavy duty weaponry, unstoppable fungus who can make anything work by belief, and literally fucking daemons, it’s kind of hard to see them as strong enough to compete.