Let's accept this, the internet is not a healthy place for discourse. The world is more polarized than it ever was, it now is easier to put your thoughts out to the world than it ever was, we all live behind the glass walls of our laptop, tablet and smartphone screens providing us a mostly false notion of anonymity. This has made web a very toxic place for discussions, especially if there is disagreemet.
"If we're all going to be disagreeing more, we should be careful to do it well."
Paul Graham wrote this in an article in 2008, which is ever more pertinent today than it was back then. In the article he coined the disagreement hierarchy.
The force of a refutation depends on what you refute. The most powerful form of disagreement is to refute someone's central point. This is in contrast to refuting only minor points of an argument which is largely a form of “deliberate dishonesty” in a debate.
The most convincing form of disagreement is refutation. It's also one of the rarest, because it's the most work. To refute someone you probably have to quote them.
While refutation generally entails quoting, quoting doesn't necessarily imply refutation. Some writers quote parts of things they disagree with to give the appearance of legitimate refutation, then follow with a response as low as DH3 or even DH0.
This is perhaps the most basic form of convincing disagreement. Counterargument is contradiction plus reasoning and/or evidence. When aimed squarely at the original argument, it can be convincing.
But unfortunately it's common for counterarguments to be aimed at something slightly different. Sometimes they even agree with one another, but are so caught up in their squabble they don't realize it.
The lowest form of response to an argument is simply to state the opposing case, with little or no supporting evidence. One simply states what they think is true, in contrast to the position of the person you are arguing with.
This is a response to the writing, rather than the writer (Which can be better than what's to come). This is a weak form of disagreement. It matters much more whether the author is wrong or right than what his tone is.
If the worst thing you can say about something is to criticize its tone, you're not saying much.
An ad hominem attack wouldn't refute the author's argument, but the author themself. Saying that an author lacks the authority to write about a topic is a variant of ad hominem—and a particularly useless sort, because good ideas often come from outsiders.
Example: Of course he would say that. He's a senator.
This is the lowest form of disagreement, and probably also the most common. We've all seen comments like:
"u r a fag!!!!!!!!!!"
But it's important to realize that more articulate name-calling has just as little weight. A comment like "The author is a self-important dilettante." is really nothing more than a pretentious version of "u r a fag."