It's a bit disturbing.
Ninety percent of opinions are crap.
However, that's not a valid criticism. BTC functioned only as the method of payment. You can't criticize the future utility of a technology based upon how someone has misused it. If that were the case, we should ban the Internet.
When evaluating and discussing any technology, you're absolutely right: it is unfair to criticize it based on a few bad examples.
However, it is fair to look at a technology and consider whether the "legal" outweigh the "illegal" ones, and if not, why.
The author makes this point succinctly.
I think this is a group that is highly sensitive to face value of statements people make and when someone makes an uninformed remark, their entirely argument is cast aside. Dissent is welcomed, but it needs to be backed by a solid justification.