“...in fact, before 1990, nobody used PowerPoint and business presentations were consequently rare to non-existent.”
No, we had overhead projectors and transparent sides to show graphs and stuff.
Perfessers used no shortage of same back in the day.
I think rock shows in the 60s used same for psychedelic displays.
I remember the days!
Used to present complicated sales presentations and complex family and homeschool ideas to groups of over two hundred just clutching pen in my hand like a rabbits foot. Changing tone of voice, looking at s d engaging members of the audience, and know one’s stuff goes a long way.
Heh, I just watched the movie “Fantastic Voyage” and they gave a presentation with lots of clever transparent overlays on their overhead projector! I completely forgot about them!
Just to prove how old I am, I will point out the fact that we used Harvard Graphics prior to Powerpoint - roughly 1985-1990.
Genuine slate chalkboards were the best!