The internet lends itself to immediate/premature responses. People read headlines without reading the article. People stop reading in the middle as soon as they feel they have something to say about what they’ve read. People don’t take the time to think about what they’ve read before responding.
And that’s before you even get to the internet’s tendency to read what’s written in the least generous way possible in order to score internet points with a response to something wholly divorced from what the author intended.
Now add sarcasm to that mix. Pulling sarcasm out of context often leads to quick-draw responses to the exact opposite of the point the author was making.