Let's say you have pain in your stomach. You tell your wife about it, your cousins, your brother/sister, your friends. They all have commentary about it.
Then you go to a specialist, you know, a guy/girl who went to medical school, did specialization for 8 years, etc., etc., and then they tell you something about it. Do you say: "Ah, doctor just gave commentary like everyone else?" Or do you actually pay attention to what the doctor says?
Juan Brown is 777 Captain. He has expertise. You and I cannot be captains in 777. But he is, because he has certain skills and knowledge that allow him to be that. So, his commentary is expert opinion based on available facts! When you and me comment on that, it is just "another dude that pulled out opinion out of his butt." But when he comments on something related to his expertise, that is different! He can actually be someone who can be involved in an investigation, etc. etc. bcs. he has that knowledge, skills and experience.
Of course, that does not prevent you from becoming Juan Brown. Maybe you should try.