How in the world did humanity keep in touch with their family before Snapchat?
Social media novelty machine 2.0.
What makes Snapchat popular is their use of pictures. Turning the thesis of your point into a totally public, 160 character or less, textual format is effort. A lot of effort.
Pictures are what they are. They're also extremely difficult to parse (no practical reason to retain your message, deletion is a cost effective decision), and they're the easiest thing in the world to make. Who wants to carefully word your tweets when your camera will do?
I am not actually sure that is actually true. My wife and I run a moderately successful travel blog and know quite a number of other travel bloggers, some of whom do it for a living.
They are all technically on Twitter for example however the overwhelming majority have hooked up a service that automatically logs in as them then publishes tweets on their behalf freeing them up to never ever actually log in themselves.
If you look at active user numbers, tweets published etc it presumably all looks great but how many real actual humans are there? I suspect the answer is not nearly as many humans as Twitter would like to publicly admin as so many have been replaced by bots.
It feels like they could radically improve the experience by locking out the bots but doing that would make it obvious how few actual humans are present.
* it is terrible with comfortably looking at a stream of images,
* for one-to-many you have to keep mailing lists around,
* filtering such streams out (to separate notifications) needs to be set up,
* ...
You could do all that with e-mail, and some people probably are more comfortable with using e-mail for such purposes, but you don't get the same streamlined UX with e-mail. Somebody could write an app that offered most of it, but sadly nobody has as far as I know.