I have to disagree with the use of vertical photos, if people can't scroll past a vertical photo, especially if it's something you took yourself, then they weren't enjoying your article anyways.

Your numbers don't lie as far as followers go, but I have not once scrolled down to a vertical photo and thought, "OK I'm done with this! That killed the story for me!" If anything it makes me look at the photo even harder if I'm on mobile or even desktop depending on how it is presented in terms of size.