Since schools don't teach reason, debate, or rhetoric anymore, the ad hominem attack is the only weapon left to the combatants. If you can't fire a rifle, pick up a brick. Television trades in cheap sound bites and thuggish in-your-face posturing, while wisdom and judgment have "fled to brutish beasts | And men have lost their reason."
Reading Churchill's account of his parliamentary experiences, I was thunderstruck that he could speak extemporaneously for hours; and vigorously parry his opponents' rhetorical blows; yet everyone would adjourn to the cloakroom afterward for brandy and cigars.
This personalization of every disagreement is the root failure, I think, traceable to a sad decline in educational standards.
In writing this, I have officially become a curmudgeon.
I am happy to advise that my daughter's high school does teach some of the items you mention, though not nearly to the depth I would like.
In observing my teenager I have noticed that the common use of onlime messaging and text results in short, blunt sentences and, often, the complete misuse of words. This happens even though my youngster is partiucularly well read. I also notice that electronic messaging is much less personal than, say, letters. It is of course much more interactive. I have seen that this reduces inhibitions and often results in 'conversations' in which there must be a winner, and therefore a loser.
I have noticed this rapid escalation to harsh 'must win' language in forums too. I have become aware of it in my own posts. The most common thing I see is when someone states something that is considered incorrect by another party. The responses look more like attacks, as if some deep offense has been committed. It seems in the brief space of a post we are tempted to state a person is wrong and rub their nose in it a bit too.
I caught myself at this a few days ago during an increasingly heated forum debate. I tempered my language and took the time to convince rather than lecture. The responses were also softer in tone.
We have to work at this. To quote The Economist style guide " Do not be hectoring or arrogant. Those who disagree with you are not necessarily stupid or insane. Nobody needs to be described as silly: let your analysis prove that he is."
This takes longer, but is somewhat more civilized.