Bang Si Hyuk isn't a CEO, but he's essentially the owner of Hybe and the individual with the most authority in that company. He can essentially dictate the actions of even the CEO of Hybe. So, when he actively engages in other company's groups, participates in their decision-making, and brings a lot of Big Hit staff to work with other companies, the system becomes ineffective. Not only does it create obvious favoritism towards groups that he's heavily involved with, but it also essentially turns the whole system into as Big Hit minions, rather than a few separate companies with their own unique images.
Why not establish divisions similar to those of JYP and SM if he still wants control over every group? It's clear that, besides Min Hee Jin, the other CEOs are merely there for appearance's sake. He's evidently involved not only in producing songs for them; it's just a component of it. Even Pledis didn't escape from him.
He's just another Yang Hyunsuk and Lee Soo Man. His ego is so huge that he wants everyone in Hybe to work with him, boosting his ego, claiming he contributed to each of their successes. But this will create tension among the companies. Min Hee Jin has every right to feel threatened, as Illit has Bang Si Hyuk as their backing, so Nj may be tossed aside at any time.
Honestly, every company would feel safer and this controversy today probably can be avoided if he just stayed in his lane and managed only Big Hit like he supposed to be.