Why is canon important?

Question

Fantasy universes have always been a world that only lives because of its supporters. The Star Wars Extended Universe surely contributed to what the franchise is today. It seems that the owner of the brand decides what's canon and what's not, but where is the logic in that? If I throw money at Disney and decide that episode 4 features Jesus Christ, would that be considered the real story by the fans? Of course it wouldn’t. I understand that if you know what's canon and what's not, you know what to expect from a future official production, but if this changes so frequently all the time, who cares? So is there reason to specify what's “real” in a fictional universe?

Edit:

The question was and is specific about SF&F. Is the canon obsession here healthy? Canon also sometimes doesn't explain things that content that got out of canon previously did. So would you answer non canonical or is it irrelevant to begin with? Also as stated in the comments, people often disagree on what's canon or not; you have to remember that there are stories where the creator/owner didn't bother to specify a canon. So, does it make sense to keep on discussing what's canon and what's not, and shouldn't there be a solution from SF&F? Something like a box you can check whether you care about canon or not canon. Also my question is about content that could reasonably be seen as canon (Like the Witcher games to the books), that doesn't include crappy written fanfic.

Answer 1

So is there reason to specify what's “real” in a fictional universe?

I assume that you're asking this in the context of SFF.SE and not life in general. As such, the answer is a definite "Yes", there is a reason. Because:

1. That's basically what many, if not most, users come to this site for in the first place.

   The spirit of the site is about studying works of speculative fiction in the context of canon.^[0]

   The reasons for that vary and may be worth exploring in a separate Meta Q&A or a blog post, but the margins of this answer are too small to fit that discourse.

2. Because if you don't use canon, you don't have a basis for workable StackExchange Q&A site - there is no objective way to score whether an answer is "correct" or not, "good" or not.

_{[0] - There are other things that the site is also for - such as dissecting the genre history and *sigh* story-identification - but those comprise a much smaller use case.}

Answer 2

Canon is especially important when it comes to shared universes or very large bodies of work.

What happens is that timelines, continuities, and even the way the universe works can all be contradicted at various levels of canon. Determining a primary canon allows users to be on the same page about the fictional universe, in a way that's internally consistent.

Users tend to prefer a certain level of canon, because going beyond that can get too messy, or seem like professional fan-fiction (such as the *What if?" line Marvel comics). It also helps to decide which media to consume, or to focus on when becoming an expert. Harry Potter experts needn't read every line of flavor text from the official video games, as that's not a level of canon most users are particularly interested in.

So, as you see, it's useful for both engaging objective discussion, and guiding users and experts to relevant material.