This thread is certainly an unusual setup, but its purpose is to highlight to prospective buyers what acceptable pricing for secondhand gear should be so they dont unwittingly get ripped off.
It also shows sellers the issues that might lead to them not getting much demand for the items they're selling be it price, poor description, bad images etc. Sometimes folk just dont realise how an ad appears to a prospective buyer.
It works both ways though, if someone drops an ad in here that's actually fair then that point will be raised too. For example the debate about avenger's fal has multiple perspectives going on.
Of course it is steeped in banter, but nothing worse than you're going to encounter at your local site. But if someone is willing to take on criticism then it's a helpful environment, if they arent then it's open season for a bit of entertainment.