When someone posts:
> You could use Redis for that, sure, I've run it and it wasn't as hard as some people seem to fear, but in hindsight I'd prefer some good hardware and a Postgres server: that can scale to several million daily users with your workload, and is much easier to design around at this stage of your site.
then the beholder is trusting not just the correctness of that one sentence but all of the experiences and insights from the author. You can't know whether that's good advice or not without being the author, and if that's posted by someone you trust it has value.
An LLM could be prompted to pretend they're an experienced DBA and to comment on a thread, and might produce that sentence, or if the temperature is a little different it might just say that you should start with Redis because then you don't have to redesign your whole business when Postgres won't scale anymore.