I don't think some of them should but the fandom community insists on it. I keep getting annoyed with Quidditch being capitalized because the way I see it, I wouldn't capitalize 'Football' all the time so I shouldn't have to capitalize a similar sport all the time. But the fandom (and probably English) has it rules so I abide.

The Lexicon is my go-to for all my plotting, query-type needs.