it gives people who don't know any better something to do and feel like they are contributing. that's the cold truth 99% of the time.
a person with a paddle can be doing the exact opposite stroke that's useful and it's barely noticeable and easily compensated for with oars. just reality.
i do hand them out in super tight stuff where oars can become largely useless and to help push off rocks,ect. and they can't hurt if you have a big hit coming up too...providing the paddlers aren't stroking like pansies anyway.
just my humble opinion.