Because you call it: a file, a slide deck, a pack or any other name for a big dump of information into a PowerPoint file. I challenge you to change your mindset around these PowerPoint or Keynote files that you put together. Call them what they are, supports for a communications occasion Call them presentations! Call them, anchor charts (if it’s only one slide). Call them pre-reads. Maybe you should call them written proposals, versus live proposals (which you should call a pitch).
No one wants to read every single little thing that you think of, just like you don’t want to read every little thing that the other person thought of. People do want to hear stories, even if the story is about how to improve their business.
Storyline first, pages second. It should never be the other way around, retroactively putting a story together based on the pages you already have.
This simple mindset shift will help you connect with your audience (and may actually end up being less work in the long run!)