@PhineasGage Pointed me here and we've had a bit of discussion about your idea
Wouldn't there be an issue with the event horizon in that although you could get tons of energy out of a black hole, crossing out of the horizon requires infinite energy?
So you could have all the power you wanted, but not be able to access anything in the rest of the cosmere
Another thing we came up with is that if a black hole is removing matter/energy from the universe, does that make a Perpendicularity a white hole?
We certainly saw that when Dalinar connected the realms, Investiture streamed in from the Spiritual Realm, so energy was added to the system