Prima facie notability only gets you so far when someone is determine to squelch a certain kind of information. I once worked on a WP article about a guy who had written dozens of books, had several biographies written about him, was the subject of any number of articles in major media (e.g. BBC), was generally acknowledged as one of the leading people in his field etc etc. The problem was that he is in an area which is (with some justification) called "pseudoscientific". Now it shouldn't really matter whether or not he's a kook, whether his ideas are valid or invalid because he is, for better or worse, an obviously notable person.

But there are people editing WP who just loathe the idea of anything that's not mainstream science staining the purity that is Wikipedia, so the article was nominated for deletion and had to go through a tedious process which should never have happened.

If a couple of people hadn't had the time or energy to defend the article it would have died, not because it wasn't notable, but just because a bunch of people wanted to censor it.