Why are people so judgemental when it comes to people's personal music taste?

Ok, I'm 25 and was born in 1992, but all the music I've downloaded on my phone consist heavily of hits from the 80s and 90s with a smaller percentage of modern 2000-2017 music sprinkled into my playlist. I'm tired of hearing people (especially older people) making comments like "What you know about that?", "You don't know nothing about that music" and such. I can see if I was listening to music from say, the 50s through the 70s, but I get annoyed by those comments because 1)I am a certified 90s baby and 2)The 80s ain't that far from my time 3)How can someone tell another person what they know or don't know about? Not to mention those songs are classics, meaning EVERYONE, no matter the age even if you're a new millenium baby, should know about them.