This is just my personal & relatively uninformed grad student opinion, but I think that in the 80s (even more so than now) it was basically quite fashionable to write theory that did not make sense in an easily deducible way. As a result, some of the more famous theorists from that period only get at abstract concepts with equally abstract writing that, in some cases, literally does not make discernible “sense.”

I think there’s something to be said about this method (meeting abstraction with abstraction), but it certainly makes for unhappy for reading. It’s also possible that I’m wrong about this. Not a specialist, just a casual reader.