Tiles were comparably slow to draw. Windows 3.1 and maybe more recent Windows had a background option called "patterns". These are 8x8 patterns of black-over-something. Second color is customizable. It could be white, but also something else. EGA/VGA hardware specific is that 8 pixel wide repeating stuff can be drawn relatively quickly. Patterns were not inside files. They are probably inside registry? Or ini files?

Whatever. The end result is that patterns are forgotten and omitted from retro background collections.