This was especially common on 8-bit and 16-bit computers to fake 'high colour' displays on machines that had only limited colour capability. They often took advantage of the fact that people were using their machines with TVs with relatively slow-changing phoshor screens, so the flicker was less evident than on a modern monitor.

e.g. Photochrome on the Atari ST, was especially impressive at the time: https://www.youtube.com/watch?v=vPsY4P8bnVw

The most extreme version I've seen of this was on the ZX Spectrum, which had not only a very limited 15 colour palette, but also limited to 2 colours within each 8x8 block of the screen. Some bright spark came up with the idea of flipping rapidly between R, G, and B frames to give (limited) per-pixel RGB. Unfortunately it did flicker quite badly because of the extreme changes in colour levels (only two levels of each channel), and the fact that it required 3 whole frames to make a single colour virtual frame.

Example here: (not suitable if you have photosenstive epilepsy!) https://en.wikipedia.org/wiki/File:Parrot_rgb3.gif