Are you saying there is no increasing incidence of diseases? Of any disease? That would be a difficult argument to make (you might want to find a citation). Note: I did not say all diseases.
It's quite possible that diseases suspect of being due to vitamin D deficiency are up, but evidence to that effect needs to be cited.
I'm not convinced that we have higher incidence of diseases today, than we did 50 years ago. At least not when you correct for age, and population size, etc. Maybe diabetes is up, but... still evidence is good.