ctrl+click was used to show the context menu with a single button mouse. At least some probably used it!

https://www.wired.com/2000/10/eek-a-two-button-mac-mouse/

"In recent years, the company has added "contextual menus" to the Macintosh operating system. But to activate them, users must hold down the control key while pressing down the mouse button, which more or less defeats the purpose."

Oct 31, 2000