If you set up facing master pages with a text frame on each, you can only set the text frame as "primary" on one of the pages. That means every other page you create from the master will be un-editable. This defeats much of the purpose of a master page, and provides no benefit.

The only semi-workaround is to connect the two frames, but this is not always acceptable. Sometimes it is necessary to keep the stories separate.

Screen grab of the process here: https://www.youtube.com/watch?v=WdvkLC0Lt5s