Why do we present?
Why don't we just hand in our report and call it a day?
Because we humans have been around in our present form for 200,000 years. If we envision those years along a yardstick, written language appears on the last two-thirds of the final inch of that stick, and widespread literacy on the last sixteenth of the final inch.
For 200,000 years, human groups have made important decisions based on the spoken word, testing not only the ideas under discussion but the character of those who propose them.
If you can move the minds of others, they see in you the ability to get things done, and they see that in your language and expression.