I would go farther and say that when credentialism creeps into a community, it's done.
That said I very much appreciate the genuine experts who post here, and hate seeing them driven away by disrespectful people.
HN walks the line between experience and openness better than any other community I know of. It's not perfect but it's still amazing.
I don't think this is really about credentials. It's about sources. What are your inputs? Outputs (opinions) are usually not that interesting without good inputs.
Sometimes you don't have any personal experience and then the best thing you can do is post a link to something interesting you read.
If you do have some personal experience, you can tell a story based on it.
It's a discussion, you're supposed to evaluate the other's arguments and exchange ideas, knowledge and opinions about the subject, not a lecture where you're supposed to trust the other to educate you.