Positive Printing Product Development

I am curious with the availability of a black and white positive paper which allows you to shoot in camera or expose slides to produce a positive print why wasn't an Ra-4 (colour) equivalent to this black and white technology ever produced? I have worked with R-3 and Ilfochrome, I am also very experienced in reversing RA-4 materials. So Im curious did any of the Paper makers experiment with designing an Ra-4 Positive to Positive paper? I certainly know a system for positives via the c-41 process was experimented with for film but failed due to grain, sharpness and colour issues. so if anyone knows weather such ideas were ever played with in Ra-4 paper product development ide love to know.