Snapchat is a CRM for college kids

Snapchat also has some sort of phenomena that makes it feel like a much lower barrier to entry than a text message.

Snapping a new person is much lower pressure than texting them.

Pictures also make it much easier for people to be involved, because you don't need to be so descriptive with your writing. That is part of the reason snap groups tend to be so much more active on snap than text groups.