Since there are no anamorphic lenses for CRT's, and they would cost a fortune if they existed, this is irrelevant in the CRT world. Am I missing something?
Yes, you are.
One of the advantages of CIH for fixed pixel displays IS to fill the panel. However, the MAIN
purpose of CIH is to present Scope movies as they were intended to be seen, that is occupying a larger area of the human field of vision, compared to the lesser AR formats, rather than the effect of letterboxing a scope image into a smaller area.
I ran two different CRT projectors in CIH mode fora total of 12 years, before I found an acceptable alternative to CRT in my Qualia.
Particularly in the case of the NEC PG and XG projectors which use 8" rectangular CRT's, CIH is very easy to implement. No lenses are required, only a scaler. The projectors adjustments allow 2.35:1 to be easily achieved with no modifications to the electronics.
So, anamorphic lenses are one possible implementation to achieve CIH, but certainly not the only one.