The list of Game Changers includes 40 cards that have a huge impact both in Commander and the kind of game you're playing
The broader picture is that OP-16 didn't introduce a hard counter to Purple Enel's engine, but the format around it has shifted
Necropotence Necropotence suffered the grim fate of those that wield too much power: Magic's best black enchantment, it got banned in most formats and now it's only playable in Vintage (where it's restricted), Timeless on Arena, and Commander
The necessity of casting it for its escape cost if you want it to remain on the battlefield can make it a hazard in EDH if you somewhat depend on your graveyard, but its a risk worth taking
If we want to get super technical looking we can say that the threat of a card is a product of it's kill index and a measure of it's survivability
Dark Ritual Dark Ritual, like all rituals that bare its name, has a built-in risk