Everything I write is of course my own opinion, the same goes for whatever you read on any history book and even physics.

Warning: Fallacy of gray detected.

The difference is in ability to infer facts about the world from assertions about facts about the world. Assertions differ greatly in their convincing power. An argument is made strong by either being explanatory, drawing your attention to a way of making your own conclusions, or by having its own truth and relevance as a powerful explanation for having been made, while for a weak argument other reasons are not ruled out.

Of course you shouldn't claim "the following is only my opinion" for all your posts, or for an explanation you read on the Internet that you think was the result of some scholarly study. If you did you would need to precede it with a meta-disclaimer: "the following disclaimer is a routine disclaimer I put on my post without regard to whether it is accurate".

I have seen some people who put routine disclaimers on their posts without regard to whether it was needed, and it was annoying (definitely to me, but also, I believe without proof, to a lot of others).

Something like "I read this explanation somewhere, which makes much more sense than the usual one" seems appropriate.

As the saying goes, you are entitled to your own opinions, but not your own facts; and you stated your cheek-slapping hypothesis as though it was a fact. The difference is important; it's the difference between saying, "It would be neat if pigs could fly", and saying, "pigs can fly".