If one has the patience, and if one has the funds. Manga is a pretty expensive hobby, when you compare it to the cost of watching an anime. Which makes it even more unfortunate when the creators of an anime cut out information assuming that you have first invested a considerable amount of time and money into other areas of the franchise.

Ideally, you should be able to watch a series or movie without feeling like the only way to "enjoy" it would be to skip it entirely and view it in another medium instead. That kind of just defeats the purpose. At that point, why make an anime at all? You could just make another advertisement for the manga. Unless that's actually all they ever intended the anime to be...a really, really expensive advertisement for the manga.