In the sense that you can refer to it for factual information - yes absolutely. Chronicle very well describes how the heroes defeated certain bosses, it very well describes how certain events unfolded. So you can refer to that yes. It is simply missing some details here and there and it is using some vague explanations for very specific topics such as the Void and the Shadowlands. Everything else can be used as definitive reference.
Sure, if it wasn't you who made a theory and was proven right, then everyone else is just lucky, right?
A bunch of forum posters "the whole zero of people" lol. Just a few hundred years ago philosophers and scientists got burned on stakes because "a whole zero of people" couldn't fathom what those innovators were doing. Your numbers mean nothing.
Sure, if it wasn't you who made a theory and was proven right, then everyone else is just lucky, right? Thank Blizzard for Pyromancer's fortune, honestly!
I mean, if you found a cave on Argus which had images of rabbits fucking and Sargeras' sword lying right next to them... I'd be very valid to theorize about Sargeras being into rabbit porn. And if then Blizzard revealed it to indeed be so, then yes, by all means you would be right. Regardless of who tells you otherwise. You'd be lucky that you found the cave, yes, but ultimately your theory would have been right.
As to the bible.... maybe, just maybe, Metzen ment it in literal sense though? Sure you cling to your "bible in non-literal sense" and "canon in its own context" but maybe that is the wrong way of looking at it
Shocker, I know right?
As to the last part - once again I ask you - source on the "not written by a character"?
It's called a theory for a reason. It is not a statement, it is but a theory. It can be right or it could be wrong. He himself seems to be very aware that most of the stuff he theorizes about might well be just wrong. But that doesn't take any credit away from his theories which were proven correct.