YWN was not created for lashon hara any more than a grocery or a shul. Anywhere people get together there is the possibility of lashon hara. The web in general, and YWN by virtue of its being on the web is included in this, is a greater source of lashon hara. People feel empowered in some way by its anonymous nature and say things they otherwise wouldn’t say.
Is the web a source of lashon hara, yes. Is YWN any worse than any other site on the web, definitely not.