I'm not tilting at windmills. This is the way to do it: by enticing, rather than shaming...one person at a time (always remember: many are silently reading along).
If you abandon good resources when you spot dilution, you are just as responsible for the dilution as the clueless encroachers. More so, in fact, because those guys usually don't know better.
Chowhound isn't a remote TV station to be passively watched. Every user's a program director. We can invest effort to make it a wonderland, or permit it to devolve. It's up to every last user. You determine the dilution. Consider: when Chowhound's gone - or useless - where exactly will you go?
Skilled chowhounds who complain about how not enough good stuff's posted anymore remind me of this:
My parents were perpetually indignant about how, as they kept moving further eastward on Long Island, the assholes from Brooklyn kept following them and ruining the rural landscape. They never realized that we, ourselves, were the Brooklyn assholes who kept moving eastward and ruining things!