I do this, but it's to block people from further-back rows from charging forward and skipping the line to deplane. Which is a problem I feel like has gotten much worse in the last 5 years or so.

I’ve always wondered this logic myself. I feel like a small book could be published around human psychology and air travel things.

If I've been confined in an uncomfortable chair for several hours and discouraged from moving around, you bet that I'll take the first opportunity to stand up and get some blood moving. I know the doors aren't going to open any faster.