Accepted answers are not necessary at the top. Here is an example: https://stackoverflow.com/questions/6121203/how-to-do-fade-i...

The chosen answer was not the best, so my answer ended up reaching the top. But note that after 7 years, my answer, although still correct, is no longer the most efficient way to do things. Better alternatives are rising up.

It's being sorted by votes. Many times, the accepted is at the top despite higher number of votes being cast for those below.

I'm not sure what the deciding factor is now, perhaps there is a more complicated scoring system happening in the background or it recently changed?

The only case where an accepted answer is not pinned to the top is when the accepted answer was posted by the same user who asked the question. Your link is an example of that.

What is the point of accepting an answer where there are multiple ways to do things, especially over time? It's a misleading signal.