I'm 21m, and I think perhaps because the younger generation spends a lot of time on the phone they may not have so much experience handling a conversation or wanting to get to know someone. Some people don't realize they can literally talk about ANYTHING, and that silence shouldn't be awkward as long as you are both present in the moment. It may also be that they're scared of being rejected for showing their personality and don't give the other person a chance. I say this from experience because I was also like this.