Why?

Firstly, it clearly states it was written collaboratively. The usual division of labour splits the task into ideas and words, human the former, agent the latter. Is this a problem? I was interested in understanding the author’s ideas; consuming the words is an unfortunate chore.

Secondly, this was published in three languages. Perhaps you missed the 日本語 and 中文, or dismissed them as agent noise? To reinforce the human/agent demarcation: without agentic AI, it would probably be quite the chore to post all three languages. The English is not written the way a non-native speaker would write it. I assume the author conversed with the agent in their native language to describe the content and conveniently got three sets of generated words expressing their ideas.

I really struggle to understand the conflation of communication-channel coding (words) and authorship.

There's no larger philosophical point here, just an empirical observation that when I trust an AI generated readme I reliably get burned, in a way that I typically don't get burned by e.g. an AI generated svg viewer or batch download script.