Meta SE seems to attract a much higher percentage of low quality, off-topic and spam questions than any other SE/SO site (Meta or Main) that I frequent.

To help keep quality on Meta SE very high would it be viable for there to be a very high minimum reputation set to post here direct e.g. 20K across all sites (or mod/staff status)?  

And then to require that all other questions arrive via migration from a per-site Meta?

There seem be some Q&As around like   http://meta.stackexchange.com/questions/89228/which-meta-am-i-supposed-to-post-on that suggest discussing/vetting issues on per-site Metas is sometimes/often preferable to posting here first.