Why check if Parameter of Interest is fundamental?

Dear experts,

I've been poking around in HistFactory to implement the possibility of blinding a parameter of interest, but I find that the sticking point is now the fact that a RooAbsHiddenReal is not "fundamental". Specifically, let's say I wanted to blind some parameter with RooUnblindPrecision, which inherits from RooAbsHiddenReal. The fact that RooAbsHiddenReal then returns isFundamental==False keeps the ModelConfig object from being written, even though this would act the same as a RooRealVar in the fit. So I have to wonder, is there some good reason for having a check for ModelConfig that I'm not thinking of?

 

Please Help !
Thanks !

I didn't find the right solution from the internet.

References:
-https://root-forum.cern.ch/t/modelconfig-why-check-if-parameter-of-interest-is-fundamental/25943
-teaser video