The idea that "human society/culture/habbit was always the same in X aspect" is as ludicrous as "human society/culture/habbit is always changing in X aspect".
For as long as any of us can remember, the average person has tried to avoid wasting their time on potentially fruitless pursuits with no joy in the journey.
Shortcuts is not just "skip the useless parts", but also cheat, lose subtlety, lower quality (as in "take shortcuts"), and so on.
In this case "read[ing] articles before commenting on them" is not "wasting their time on potentially fruitless pursuits with no joy in the journey", it's the very basic prerequisite for responding to an article.
And yes, there was a time when this happened less. In the mobile and social era, people are skimming more, jumping around from text to text more, and do focused reading of articles and books less -- this has been studied and written about several times (e.g. here's a high level article from a book author on the subject: https://www.theatlantic.com/magazine/archive/2008/07/is-goog... ).
