I don't think the article is saying "just start coding", it's saying "when you code, use what you know instead of working on the tooling".

The best code is no code.

Haha. I see what you mean. Lack of market is the #1 killer of a startup.

That's not what TFA is talking about. This is not lean startup advice.

It is advice for engineers to focus on the utility of the thing they are making for other people, rather than focus on the toolchain that allows them to build the thing.