I don't recall there being a policy that discussions be restricted to art music. In fact I enjoy having non-art-music included in the mix.
Firstly, it is next to impossible to clearly define what classical music is. For instance is Sorabji classical ? Is Frank Bridge ? Is Billy Mayerl ? Is Kapustin ? Is Scott Joplin ? Is a composition written yesterday in Bach's style classical ? Is a Chopin piece still classical if the player fiddles with it or improvises a section in it ? Perhaps most might agree that classical music is not improvised, but in these days of digital processing it seems an anachronism to insist on the existence of a piece of paper. What about transcriptions ? Are the Waller and Morton solos now classical because they have been written out?
There are other forums that have attempted to confine musical genre into a forums organizational structure. If you prefer this type of "organization" why not go where it already exists? There is no need to make Pianostreet like everywhere else.
Blah blah blah blah . . . Don't be obnoxious.