Vox's fall from power was great
Voxs climb to power in hell mirrored his life. He steps on other people and uses them to his advantage. On his own, Vox is pretty weak, just like Alastor said. He needs Velvette and Valintino to prop him up. He goes to Alastor when he first enters hell and asks for his partnership. Partly because he liked him, but mostly for what Alastor could offer him.
Valintino owns one of the biggest industry's in hell, with many many souls under his contract. Velvette is young and competent with modern day technology and social media.
He couldn't have become a powerful overlord without them. He would not have such a massive following. He uses Liltih's old campaign and rebrands it for himself. He uses hypnosisis to control sinners, where Liltih used her voice to empower them.
He can't build wepons for himself, he needs Carmila to do that for him.
Vox can't even be declared the strongest sinner in hell without Charlie being forced to say it. On his own he can't really do anything, which makes his punishment SO fitting. Being torn apart by the people he used and betrayed. Left as just a pathetic little TV head who has to watch and whine and things don't go his way.
This is a much more satisfying end to his arc than if he was just killed. As he said, Vox doesn't care if he dies as long as Alastor died, too.
Besides, he died at the height of his fame when he was alive. He never saw what the world looked like when people stopped caring about him. Now he will. He has been well and truly humbled.
I hope his punishment from the other Vees is something really goofy. Like Velvette uses him to play makeup tutorials for the new contracted souls or something.