Revoking a CSCA especially towards the end of the lifetime (passports are usually valid for 5 to 10 years) is probably not economically possible since it would

Revoking a CSCA especially towards the end of the lifetime (passports are usually valid for 5 to 10 years) is probably not economically possible since it would invalidate millions of passports all at once so you have to fall back to optical features anyway