I prefer paragraphs to be more than one sentence because fragmentation can be just as unclear.
I wrote user instructions for every app that I developed. My last manager told me that it was not necessary. What happens if there is a question and I am not there? My poor backup might have to dig into the code just to answer something simple.
Shorter attention spans do demand shorter paragraphs.
I hit the same clarity concept when explaining how to solve an algebraic equation.
A girl came up after class and said that she got good grades in high school and college algebra classes, but this was the first time that she understood what was happening and why it worked.