why are so many people so comfortable making this assumption, based on writing style or a checklist of supposed tells or notoriously unreliable detectors, and making kneejerk accusations like they can do no harm and are already settled fact? It's one thing to feel suspicious or disregard the article yourself, but being so incautious about making public accusations without solid evidence is another.

At best, you've identified LLM use. At worst, you've insulted a human writer. Either way, you've derailed the conversation away from the topic at hand.