@Brainship It's easy. Doesn't take much graphical power.
@Brainship Well, if you think about any alternatives, they all require more effort on the part of the game console to display. Where a flash is just "replace everything with this color", other effects require more things to be specified. And then anything that warps the image requires image processing hardware that nothing prior to the playstation really had, though the SNES could do some very limited squash and stretch stuff.
@Felthry ah didn’t know that tbh? :0