Matte paintings were used before the dawn of competent computer graphics to simulate a larger/more dramatic/exotic location than can be achieved in a film studio. Paint was directly applied to glass, which then sat between the camera and the actors (leaving a clear section to capture them).
AFAIK mattes are still A Thing in filmmaking, but they're obviously not done with actual paint on glass.
The best use of CGI is when audiences are wrong about which parts are CGI.