I see lots of questions with no answer selected, but a completely viable and correct answers on them. How often do they? Do they at all? If not, they should. Also, I have lots of answers several months old that are completely correct, but no answer selected. I see this with lots of other users. How often do the mods go back and select BA on questions with none?
It takes more effort than you might think. We get around to it whenever we want to sit down for a few hours.