Yes, as i wrote in the part you quoted, back in the 80s and 90s this was a problem however nowadays the dithering is an aesthetic choice and not a CDE limitatio

Yes, as i wrote in the part you quoted, back in the 80s and 90s this was a problem however nowadays the dithering is an aesthetic choice and not a CDE limitation. You can even see in the screenshot the Firefox icon using true color output (it sadly doesn't use alpha blending though, so this might actually be a CDE or Motif limitation - it shouldn't be impossible to fix it as the X server can do alpha blending nowadays but it needs someone to figure out where the limitation is and implement it)