Yes, we're looking for some other human sharing something interesting. There is no requirement to put things out into the world. So when somebody shares something to a discussion board like HN the hope is that if I'm going to spend my time reading it, they spent the time to write it. If I wanted to read an AI response I could just ask it "Tell me about how you could organize an entire business in a monorepo".

Somehow I suspect this would be a nonissue if it easy to determine whether an article is written by AI or not.

Agreed. Especially when a lot of people just pick out x, y and z thing as if it's the definitive sign of AI, disregarding the possibility of it being normal outside of their own writing and what they read. Not to mention cultural differences. That certain characters or ways of structuring text have become more pervasive lately is a sign, yes, but it does not mean that the presence of it in a text is anything definitive towards the use of AI.

It's almost as if when you seek to find patterns, you'll find patterns, even if there are none. I think it'd benefit these kinds of people to remember the scientific "rule" of correlation does not equal causation and vice versa.