@futurebird
Like for example: earth biochemistry happens in water. And any time a proton needs to get added or subtracted, you just grab one from or give one to a passing water molecule. But moving electrons around is A Whole Thing. Tons of biochemistry is centered on electron transport.
And the cofactors (vitamins, really, in people) used for this are these kind of aromatic small molecules, little mostly carbon rings with some other atoms and some double bonds. …