It is hard to communicate an idea for a new song without the help of the full band.
- When you play the basic idea on one instrument to someone else, that person misses the context that it is in your head: the result a few bland chords in an obvious sequence.
- The same can happen to you. You had that brilliant idea, but when you get back to your note book the next day, the scribbles sound like a few bland chords in an obvious sequence.
The same is true for your presentation. Your audience is missing the context that is in your head, and the slides / your story is the only thing they can rely on.