The topic of the article was ragging on internet commentors in tech forums for not being subject matter experts in every topic they discuss. It's one of the worst takes I've read in a while to be honest.
As long as everyone is being reasonably descriptive, it's perfectly fine for anybody to discuss anything.
For example, "ip law is bullshit because of {my_differing_moral_base_presumption}" is an absolutely fine thing to say, and argue. You're not being prescriptive and nobody is ill-effected, or directed to be ill-effected, by your opinions stemming from your differing moral base.
Furthermore, claims about what you think the outcome of something might be - given your limited knowledge - are perfectly fine too. For example, "I think a reasonable court would find that the claim was bullshit because it's a 30 second segment of the song mixed over some anime, out of a 50 minute talk. It's clear the intent wasn't to republish the work for profit."
There's absolutely no problem with this from the perspective of healthy conversation. You're taking a good faith approach to the discussion and saying what you think might happen given your knowledge. You may ultimately be _wrong_ but you were never saying you were _more right_ than subject matter experts anyway.
Basically the only times it's a good idea to dump on people is when someone ignorant is being prescriptive. "When you're licensing your work you should add {some_clause} because of {bad_understanding_of_law}". That's when it's harmful. Or, if you're acting in plain old bad faith.
So if the article was complaining about this kind of harmful prescriptive talk, I'd agree, but that isn't at all what I'm getting from it.