Stack Exchange management wrote a big post about why it makes sense to spin off some topics or areas into their own stack sites. If I have an Ubuntu question, it would make sense to ask it in the Ubuntu site. If it's a WordPress question, there's a site for that too. And Apple questions, there's a site for that. Let each expert focus on his area. This all makes sense to me.
What doesn't make sense is that there are so many questions regarding such areas still popping up here on SU. Why is it even allowed to post Mac questions on SU? Or Linux questions? Or Gmail questions? Why aren't they closed and the asker referred to their respective stack site?
I understand why people do this. Of course I'd prefer to post my question to a SU audience of ~40000 rather than to an Apple audience of ~1400 -- the more people see my question, the better answer I'd get. But this is exactly contrary to the Stack Exchange management's arguments! So what gives?
I want guidelines that people can understand and follow.
Either allow questions even on topics for which other sites exist -- and never ever close them! --
or close such questions immediately and refer the askers to the proper sites!
I'll appreciate any comments and explanations.