We have access to infinite amount of "snippet" information. We want an "answer", now, and not the reason of how and why we arrived at those answer in the first place. Lots of people searching for just an "answers" and not thinking, and we end up in a world where we have far easier access of information than any other period in human history and our time to think and learn has been taken up by social media and other easy access entertainment.
Another problem of long reading is the quality of writing has degraded over the years. Or may be we have far too many information so the average or median quality are lowered.
The last great pieces of long Tech article i enjoyed were written by Anand lal shimpi, founder of Anandtech, but he left the site and went to work for Apple.