No, it's really not. I mean sure there is some of that, but you're wrong if you think that's all people use Snapchat for. People share things on Snapchat to their close group of friends which means you're willing to say things you wouldn't say in public about people, say things you wouldn't want your mom to hear, pass secrets around, or just talk in a more "anonymous" way. It's the difference between somebody taking 45 minutes to pose for and edit their next Instagram post vs. sending 45 snaps in a minute without even looking at the picture you take. It's almost like Casey Neistat's Beme--Snapchat encourages you not to care about what you send because it will be gone in 3-10 seconds.
It's the reason sc was invented but definitely not what it has evolved into. I'm aware there's porn accounts but the majority usecase is simply a low-friction 0 commitment method of sending pictures/thoughts/happenings
Unedited content is more referring to the style of posts. I joined Twitter in the phase where people would Tweet "My Chipotle server gave me a lot of rice today." Now of days, if you're an average Joe, that's a Tweet most people brush over. With Snapchat, though, it transforms the message of that Tweet in today's generation much cooler simply by way of pictures. A candid photo of a Chipotle bowl that looks delicious? That once boring Tweet is now more interesting. Both are "unedited" such that they are candid posts, but Snapchat found a way to actually make the uninteresting fairly interesting.
Instagram (basically personal brand/image management, checking out latest styles from other people, styles she can actually afford)
Snapchat (personal circle of friends, unedited content)
YouTube (lifestyle bloggers)
Facebook is dying in their demographic.. pretty fast, except for Facebook pages for things she’s interested in