Firstly, what does having a FFS or FTD allow you to do as a training organisation that an FNPT (1/2/3/MCC) does not? e.g. I can see that an FNPT II and MCC FNPT would allow you to run IR and MCC courses. i.e. what can you do in a FFS or FTD that you may not do using a suitable level of FNPT?
Many items of type rating training courses, skill tests and proficiency checks require full flight simulators (FFS) or higher level training equipment, which - coming from a simulator - would be the actual aircraft. Other items, such as Mach tuck under, must not be executed in real aircraft, but have to be flown in a FFS.
For details, see Appendix 9 to Part FCL of the Air Crew Regulation (Commission Regulation (EU) No 1178/2011 of 3 November 2011).