I get the impression Snapchat is a sort of 'fun' thing, wheerby photos and silly messages are sent but only 'stay' with the recipient for a few minutes. I can't see any real uses for it other than 'larking about'.
There are lots of apps that aren't useful or appropriate for me, so I don't worry if 'the kids' think they are essential.
I never ever want to be glued to my phone in the way some of them seem to be.
Whatsapp sounds useful but I want life to be as simple as possible, therefore I keep texts and photo-sending to a minimum. My mobile is for emergencies only really. I prefer not to send or receive texts unless they are a matter of real importance.
I am capable of doing it and refuse to be seen as a dinosaur just because I am not in permanent contact with friends and relatives.
Oldies are perfectly capable of using modern technology and most of us understand it and are happy to try new things. That applies to me, anyway. I like to think that because our need for perma-contact with people isn't so great we are discerning rather than out of touch, or ignorant.