Back many moon ago (1987) my nephew showed me a two monitor setup on a then new Mac II. I was suitably impressed. My experience before was possibly two monitors on a PC, one monochrome, and another color. Not much integratoin between the two at all.
The moving between two monitors with the mouse pointer truly amazed me.
Of course now it is second nature, but 35 (more or less) years ago. it kinda blew my mind.
Time marches on.