Part of the problem is that the discourse on methodology is mostly conducted by people who don't themselves do the work. Imagine a bunch of managers working out a "process" for, say, mathematicians. They'd be laughed out of the room.

I think good methodologies may eventually be worked out for software, but it will take generations and they won't look anything like what people (especially project managers) expect nowadays. Agile was actually a step in the right direction by comparison with what preceded it. But it's decadent now, having inevitably been overrun by consultants and vendors.