BUT (and it's a big but), it adds a second axis of subjectvity. Already, I'm out there talking about a thing which I think is "interesting" and "worthy" subject matter of other peoples time. Now, I'm adding "and is delivered in an entertaining way".
For me - that's humour - both in the delivery, and in the slides I show. But - like anything - it doesn't always land.
And, when it doesn't -- it's a very very long awkward talk. I've been on speaking circuts where a conference goes to multiple cities (same country), and the talk went down very well in one city, and bombed in another. Things like timing matter (after lunch sucks).
Also, The author lists the requirements as "inform, educate and entertain" -- and I'd add -- "in that order". I've cut things from my talk because they were funny (IMO), but ultimately didn't support the content of the talk enough. After all -- This is a tech talk, not a standup routine.
All three are very hard to do well -- but I do agree with the author in that's it's the speakers job to do all three.
It is very important though. It's very easy to lose an audience, and the truth is a lot of the speakers before you will likely range from slightly boring to extremely boring. The audience can be primed to totally clock out if you don't grab them immediately and keep them for the whole thing.
If you want to keep people's attention, make every slide as minimally simple as possible. Like one diagram and maybe a few words. Listing out bullet points of full sentences might feel efficient but it's no better than just saying what you would have written. And lots of text is a lot more glaze-inducing for most of the audience. You can point to supplementary docs for detail.
Another idea is to break up longer talks (30min+) in two with some slides of nice photos you've taken.
Humour can work in presentations but it's really hard to pull off well. A lot of jokes rely on things like shared background/experience/cultural touchstones, so tricky to do in a conference where you might not know those things about your audience.
If you do use humour, I'd recommend not making it core to the talk, so if people don't get the jokes, it doesn't ruin the talk for them. Also generally use it sparingly, the odd meme can be funny, one on every slide probably not a great idea.
If you want to have something for attendees to refer back to after the talk, a complementary blog/whitepaper is a better idea than putting all your details in the talk slides