RE, a good point.
If the reason is danger, then having books and computers at home should exempt one from observing N.N. Or is it minhag avoteinu that overrides a Torah mitzva?
If the reason is mystical, why don’t we follow Jewish calendar instead of following Julius Ceasar, Pope Gregory,
Which groups do NN and which do not and when? Maybe we can reconstruct tradition from geo/social distribution?