I'm sorry I didn't reply to this during the conversation, but am traveling this week. IMO the short answer is that questions like "why didn't APL take off" presuppose an orderliness to history that doesn't really exist. Plenty of historical factors (e.g. market dynamics) can intervene to prevent an idea from taking off. Presumably if an idea is really superior it will be rediscovered many times in multiple forms, and one of them will eventually spark.