I don't think anyone has implied that no one should dye their hair. People should do whatever they want. If they want to be 40 with purple hair or 80 with pitch black hair or 20 with pure white hair, that should be accepted without question. It does seem that grey/white hair is the least accepted regardless of a person's age and I think that's a shame. People should be able to feel good about themselves with or without hair dye and plastic surgery.
I knew few women of my grandmothers and great aunts generation who dyed their hair. They all had thick, healthy grey, white, or salt and pepper hair. Most of the women I know from my mothers generation have dyed their hair constantly for 30 - 40 years. Most of them have very thin, weak hair. Luckily my mom stopped dying hers years ago and she has lovely thick white hair.