Quotes from famous people, preferably dead white ones, were mandatory in speeches. No one had thought about it and realized the script went a lot smoother if the speaker just explained that Franklin was among the American pragmatists who recognized time is indeed money.
That was then. Now, if a speaker interrupts the flow to insert a quote. Which, likely, will be delivered ham-handedly. That speaker would lose our attention.
Back then, there was also the 20-minute rule. No speech was to go longer than that. Currently, if you are delivering a talk on doing search engine optimization (SEO) right, the audience would sit for days. If the subject is important, audiences demand you include every bit of information and insight. Do anything less, and it will be rotten tomatoes.
A third development is the need for total authenticity. The delivery has to be one transparent human being addressing fellow human beings. The relationship is horizontal. After all, we are all trying to put together solutions for saving entities like mankind and the U.S. economy.
Even as recently as the late 1990s, the positioning was vertical. The expert pontificated. Mostly now, we no longer even believe in experts.
On June 30th, I am giving a talk. It's to college students about how to get a career going. Everything will be framed as opinion. There will be no quotes. It will run a hour. And the takeaway will be: It's you who has to be your own best authority on having a successful career.