Why do we use OK-Cancel in confirmation dialogs and not "Do It"?

This story comes from Andy Hertzfeld's book Revolution in the Valley.
The book contains many memories about all those fantastic years, when they could feel the excitement of creating such a novelty product, how Macintosh was.

One of the users testing the confirmation dialogue in the software felt flummoxed by "Do It" button text, so the text was changed to "OK".

I like the story. We can see all kinds of prompts and messages in the line of business applications.

To communicate with users clearly is our never-ending challenge for programmers. I would not ask you how many times are you feeling lost, while doing something?