How do you know this person is a "domain expert"? It's frankly outright foolish to give any weight to an anonymous "expert". Even then an anonymous comment could be valuable if there were links to sources demonstrating "consensus among domain experts", but nothing of the sort was provided.

Your comments about what internet forums are for is completely unrelated and also incorrect. Internet forums are for whatever someone is willing and allowed to discuss.

I don't know they're a domain expert! Hence the 'heuristic' part. I do know that in the course of normal conversation I'm not owed 'links to sources'. I can certainly ask for them if I can't figure out how someone arrives at their conclusions but it doesn't make reading comments without them (or without a list of the commenter's verifiable credentials) 'outright foolish'. What you are describing doesn't sound like a general purpose forum anyone would want to participate in. And the way you're describing it sounds outright scoldish.