I don't really understand what the post is about.
I don't think it's natural for a software engineer to want to build a "software factory" because I have never heard of anyone doing that. I'm sure it's a thing.
What I see everyone doing is just building software, incorporating their feedback into agents.md, skills, etc, to make their harness better. Is that a factory? Should people not do that?
I still don't really understand.
The productivity gains of people using their own "custom" harnesses and agent tooling (e.g. letting agents talk to eachother over a messaging board) is questionable at best a waste of time at worst. No one I've talked to is actually applying the scientific method and measuring how long and how many tokens it costs to get a certain task done with just a plain chat input vs all this custom harness/tooling crap.
All you need is the source code for your existing project and the claude code/codex/opencode cli and boom, you are ready to ship. Most people doing the impressive stuff with AI are just using it, not building harnesses or "agentic" tooling.