I assume that it is primarily not about DirectX (or specifically DirectDraw) compatibility but about W9x games assuming that they can use DirectDraw to setup pa

I assume that it is primarily not about DirectX (or specifically DirectDraw) compatibility but about W9x games assuming that they can use DirectDraw to setup particular video mode, somehow get pointer to directly mapped framebuffer with particular organization and pixel format, write into that directly and completely ignore DirectDraw after the initialization.