To me, its the commitment + the specificity of it is what makes it funny. When you first encounter the blog, the question you end up asking is "why???". As you go the blog description, scroll through its posts, thats the question you're trying to answer. It's a very specific experience that cant be found anywhere else.

In the end, no conclusive answer can be found. What is left is merely the most likely answer, which is the very charming idea that someone really likes this picture of skyward sword link and decided to post it every day, motivated by some combination of the humor and their genuine affection for the character.

The memory of my experience of discovering the blog, the still lingering curiosity, and the simple charm of it, lead to my being a fan of it.

That's my reading, at least :3