If you've scrolled through my work you'll notice that most of mine fall in the 2 min to 5 min read time slot. That's all the attention span a lot of people have. Plus there is so MUCH to read that no one wants to spend several mins on a single piece. Then you have ESL readers that may struggle to understand longer pieces. There are those who read as they commute to work. Lots of reasons to keep them all short, sweet, and to the point. (And I never participate in contests! lol)