I seem to have come to much of the same conclusion as you have reached, though approaching it from the direction of economics and the social sciences rather than from biology - that there is a body of what have been calling "general empirical theory," or "general system theory" in your excellent terminology, which is of wide applicability in many different disciplines. I am sure there are many people all over the world who have come to essentially the same position that we have, but we are widely scattered and do not know each other, so difficult is it to cross the boundaries of the disciplines.
Boulding (1953) in letter to Bertalanffy, cited in: Ludwig von Bertalanffy (1968) General System Theory. p. 14