why wouldn't this simpler code work?

I've looked into this page and a variety of sources on this and I have to admit I'm inclined to agreed with you. I think Lucian has made this harder that is actually needed to be.

Where your function would differ over the existing one is when does not contain a perfect sequence of integers. i.e. {4,1,2,7,3}. However, I can't see when it would be logical to do this.

I'll await feedback from Lucian, but upload you code as a draft for now.