The problem is that this forum, and social media in general, is viewed by a lot of people, certainly orders of more magnitude more people than actually comment. Comments such as yours misleadingly take advantage of human social traits, such as attributing more truth value to someone with authority, and avoiding people who have been negatively labeled because they must be outcasts. There are potentially thousands of people who's respect of Graham Hancock has been decreased to varying degree due to your statement. Using appeal to authority and ad hominem name calling are the most basic of logical fallacies and should be completely discarded.

This is completely unrelated to whether Graham Hancock is actually a fraud or not. The problem is with your comment, no matter who you are talking about. Anonymous authority on the internet is worthless, as is name calling. As a supposed academic, you should be providing sources and examples, the absence of which makes your statement about being an authority on the matter suspect.

I take issue with this because this sort of mechanism is currently used on social media to wreck great havoc on society, especially in the US where people's lives are destroyed and horrible politicians get into office due to supposed authorities calling people names on the internet. It's a far worse issue than you are acknowledging. The whole point of social media is to spread ideas. You are not an island.

"... especially in the US where people's lives are destroyed and horrible politicians get into office due to supposed authorities calling people names on the internet."

For someone railing against unsupported assertions, that's a whopper. We can stipulate horrible people have gotten into office and that people are calling other people names on the internet, but the arrow of causation is not at all clear.

Addressing your point more directly: I don't think the problem is people making insufficiently footnoted comments so much as readers accepting things that align with their predjudices uncritically. As such, I don't see what is gained by attacking someone for commenting in a casual style.

> "... especially in the US where people's lives are destroyed and horrible politicians get into office due to supposed authorities calling people names on the internet."

Is this not common knowledge? Do you not use the internet at all? Graham Hancock isn't even known by most people let alone the quality of his research.

Internet forums are typically for conversation not formal arguments constrained by some catechism of 'fallacies'. Domain expertise, consensus among domain experts, etc are perfectly sensible heuristics one can apply to claims.

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.