I get your point, but (if I understand you correctly) I’m not sure I entirely agree. Yes, I’ve been playing live for quite a few years and am very cognizant of getting a good sound in the mix. And, I do agree that someone who has never played live may give unhelpful advice or be unaware of what goes into that, but that doesn’t mean all of that player’s input is of no value. Sure, some or much input may be derived from internet sources, versus personal experience, but some of those internet sources may be helpful, in their own right.
However, approaching this from the context of a music forum, I’d rather a bedroom player feel welcome and encouraged, rather than just shut down because he hasn’t reached the status of “Live” player or “Recording” player. Even if some input is, initially, not the best advice, shutting down such a player could be discouraging. I would rather see the more experienced ones come alongside and attempt to guide the person rather than expecting the person to just keep his thoughts to himself.