I think at least partially, it's not an anti-LLM stance, it's an anti-"kill my website" stance. Many LLM crawlers behave very poorly, hurting websites in the process. One result of that is that website owners are forced to use things like Anubis, which has the side-effect of hurting everybody else, too.

I prefer this approach because it specifically targets problematic behavior without impacting clients who don't engage in it.