Just a sign of how deeply flawed the base of our thinking about information is these days. Everything is public by default, in part because of the warped Google/Facebook worldview has been drilled into us by the likes of Schmidt and Zuckerberg.
Seeing it used that way was a real "a ha!" moment. I'd love to know what Venmo's activity looks like around the time that people are putting together or paying out office sports brackets and such.
1. It's more honest. With Facebook, you are given the illusion of sharing information only with your friends, but it's actually ...with your friends, and Facebook, and anyone Facebook chooses to share it with. Cambridge Analytica being the highest profile example. When you tweet, the expectation is that whatever you said is now On The Internet, a matter of permanent record.
2. It opposes the network effect. Twitter doesn't force me to create an account in order to view a tweet. Or, from the other perspective, if I post on Twitter, I'm not requiring anyone who wants to read my stuff to sign up as well. It's closer to a microblogging platform.
e: On second thought there probably are exceptions - I'm not worried that something backed up to Backblaze will be leaked, for example. But a random flash card app? I'd assume that info is public. Maybe I'm just paranoid.
This is why it's important for things like password managers, personal documents, etc. to be encrypted client side if backed up or hosted somewhere on another machine that isn't yours.
A good line that I've seen people use on this forum: "the cloud is just somebody else's computer".