Imagine the same advice being given to standup comedians: “Bits should be a medium size, not too long.” “Avoid long words and try not to alienate your audience”. What a snooze fest!
A good talk is a performance piece. It should be simultaneously entertaining and informative. You do that by using narrative, by connecting with the audience, and by being compelling (via emotion and showing your own pleasure to the audience). If the audience is so busy reading your slides that they don’t pay attention to you, you’ve failed as a speaker.
I’m going to take a big risk here. I challenge you to go watch any great talk online, in just about any field. Watch Steve jobs introduce the iPhone. Watch a standup comedian. Watch a tech demo. Or your favourite conference speech. Or any popular YouTuber. They will almost never be this kind of talk, with subheadings and the appropriate amount of “supportive graphics”.
These “rules” are well meaning, but mediocre. They might even be helpful for a lot of people. But you should aspire higher. Aim to give a great talk. Not just a talk that’s slightly less horrible than your peers.