I just read something not too long ago about the first stars in the universe. Apparently, there were many truly monster-sized stars that quickly supernovaed and threw out tremendous quantities of heavy elements, from which new generations of stars and planets formed. So there was a greater concentration of the heavier elements in the early universe than one might imagine.
“So there was a greater concentration of the heavier elements in the early universe than one might imagine.”
Not to mention there was a whole lot less space separating these elements back then so accretion would have happened at a much faster clip than what’s happening today.