Character-based hardware only stores the characters and the grid instead of the full bitmap for the frame, which is very efficient memory-wise. Tile-based hardware (e.g. most console graphics chips in the 8/16 bit era) also had scrolling and layers, and was extremely memory-efficient as well. With bitmap displays you already store full frames.

Sure. Maybe I should not have written 'blitting' when the rectangles are not copied from one memory location to another but end up directly on the screen.

My original point that putting a fixed number of small and fixed rectangles on a screen is more efficient than line drawing still stands though.