I really liked the idea, "a presentation, being about content, not about slides". But enforcing 3 slides per presentation is ridiculous.

A presentation should be balanced between content and visuals. Content should be presented in a manner supported by visuals. You liked the graph because it was essential and supporting the information being transmitted to you.

Also, filling a presentation with unnecessary information and talk would turn the audience off and bore them.

So stopping and thinking before doing any writing down or creating any slides is good behaviour leading good presentations.