I have I say, I sort of agree with you, OP.
Chances are, if you're 50 or 60, your hair is probably pretty grey. I can say this with some authority, because pretty much all men aged 50-60 have grey hair.
Therefore, women age 50-60 with jet black hair have probably dyed it that colour. Ergo they're altering their appeance in an effort to look younger, because in our society younger=better.
The unfortunate outcome is that, more often than not, they actually look worse. The softer, grey look is more becoming than the harsh, unflattering jet black look. Or, if they really don't want to be grey, then something less harsh than jet black is almost certainly going to make them look better.
This is one of those things that you can think in the privacy of your own head - or share with a partner or good friends you know well - but admit it out loud to an unfiltered audience, and you get slaughtered. 
We all have wrong thoughts from time to time; the mistake is admitting them on AIBU.