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)
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)