I think the title of this should be "BLACK HOLES SERVE MULTIPLE FUNCTIONS IN OUR UNIVERSE"... would you agree?
No, I don't agree because nothing serves a function, it's all about the balancing of forces, like the size of a soap bubble. Or memory foam in a compression chamber.
The assumption that a function is served sounds like the function precedes the thing itself, it doesn't.
In this universe of forces life is a balance, the Cyanobacteria may have purified enough oxygen to support modern life, but it can't be argued that that was their function, it's just what they did.
Also function indicated responsibility, and responsibility indicates authority.
There's no authority, just a bunch of pushy superstitious apes.