Setting aside copyright/commercial/other aspects, a thought about writing blog posts that LLMs train on. When people write posts, they (a) feel good about helping others, and (b) hope to get some credit and visibility for doing so.

When mediated through LLMs, no longer the satisfaction that your consumer is a human (who might comment, thank, share, etc.); nor the cred that comes from people remembering the author, posting on HN, etc.

That is, it totally destroys the incentive structure.