I would be interested to hear if this is the case, particularly in CMYK conversion. :-)
The CLUT's (Color lookup tables) for an RGB to CMYK conversion are pretty carefully guarded by Adobe, and rightfully so. Their color lookup tables are the most flexible and powerful ones in use by the graphics industry, involving complex and robust gray component replacement and under color removal, across a variety of printing stock profiles and ink standards. The only ones that come close and excel are proprietary tables by Scitex and Dainippon Screen. This is deeply integrated into adjustment for Postscript output as well.
In The Beginning there was a program called Color Studio we used for a while, eventually bought by Corel (I think.) A close comparison of CMYK outputs quickly revealed its inferiority.
If you need quality output for printing, you will want to use Photoshop.