It self-corrects on generational timescales, which is arguably not good enough. The last "fad" of conglomeration happened in the "go go years", and a generation

It self-corrects on generational timescales, which is arguably not good enough. The last "fad" of conglomeration happened in the "go go years", and a generation of business and finance types learned it was a bad idea. Now those people are all retired and a new generation is learning the lesson.