Since this community is for any kind of question, I’ll answer, but I get the vague sense that you don’t really want a genuine answer, based on the inherent bias you included in the question (calling someone older than 20 a hag is pretty uncool, for example).

But here goes: people have different tastes. Different things turn on different people, and your lack of experience being aroused by older women says nothing about the legitimacy of those who are. Also being 21 for example, is still considered very young by most people. Your question presumes that everybody in the world must only be attracted to very young women, and frankly that’s a bit strange and just not how the world works.

Try to put yourself in some other people’s shoes, and I think this question would answer itself. Your sexual preferences are not everyone’s preferences.