yes I found de-selecting the blog page under Appearance – Settings – Reading quite confusing too, I haven’t seen another theme do it this way (but then I’m no expert at all so perhaps they do).
However, saying that it was initially confusing, I think it is also quite good because it gives you a lot of flexibility with the blog layout.
If you have the blog selected under Appearance – Settings – Reading then you get the sliders/header on your blog and some people who are using it for a blog homepage will want this.
If you de-select the blog under Appearance – Settings – Reading then you don’t get the sliders on your blog and that works well for people who want a blog not as a home page and to fit in with a website style.
So, you get the option from this theme which is good in my view.