You have to realize that until Music Man, the basic choices were Fender Jazz, Precision, Rickenbacker, Guild and Gibson. Despite how they are lionized now, most players thought early 70s Fenders were pretty atrocious. Alembic was from another planet-there were NO active basses before that. Virtually every major bassist (JPJ, John McVie, Entwhistle, David Hood, etc.) got one. There are a lot more choices now, of course.
The funny thing about Chuck is I remember reading an interview with him in Guitar Player in 1976 where he said, "The Alembic I won't even buy-it's not a bass at all." Of course, several Ken Smith, Warrior, Spector and other brands later he's obviously a changed man.