That has been said many times on Gransnet, and the number of responses is very low compared with some social networks. It is not generally thought as fun to keep up an exchange with these halfwits, so not many keep it up for long.
Sometimes it is worth commenting on a dodgy post, though. There are occasional naive posters on GN who believe that someone who has put forward an image of themselves as a nice, innocent, person, perhaps seeking enlightenment on a tricky topic they don't understand, or wanting support for a dreadful situation that they describe in detail, must automatically be genuine. So they get drawn into a correspondence that gets more and more bizarre.
It doesn't happen often, but there have been cases where these posters have been rumbled by GNHQ and suddenly vanish from the scene.