Are Not Mutually Exclusive - Tumblr Posts

This is something I'm seeing more and more on AO3 that I'd never seen when I first got into fandom stuff, so I wanted to find out how you all feel about it.

What are your thoughts about seeing posted fanfiction that isn't commissioned, where the creator says that they have never read/watched the source material? For example, someone putting out a fanfic for a show they've never watched that includes the tag Author Has Never Seen Suchandsuch.