Somewhat more disturbing is that when a person uses an app they are also often (but not always) agreeing to share their contacts/friends information as well as their own. Imaging that happened in real life:
Random Person: knocks on your door
You: opens door, hello
Random Person: Heeey I've got this cool IQ test you can take for free!
You: .. umm.. ok.. what's the catch
Random Person: Just share with me a bunch of your personal information, like show me your photo albums man.
You: not sure about this..
Random Person: Aaaaand a bunch of information you happen to know about all your friends
This starts to seem a wee bit creepier. I'm virtually positive that most people don't realize the latter part happens in addition to them sharing information about themselves. Unsurprisingly there was a HUGE uptick in these sorts of "free tests" (which were also personality profiling) right before the last several elections (yes several).
Again, it only matters as much as you're willing to share stuff and what you believe is/is not public so its mostly a mismatch of expectations. The recent kerfluffle also involved some likely TOS violations or at least some downstream contractual breaches that look like TOS violations (who knew what when determines culpability and I don't know any of that). I'm mostly with Roger, if you're putting things on the internet they're pretty public for the most part even when you don't expect them to be initially (I don't however share his trust in TOR for various reasons
).
I do have to unfollow or otherwise hide a fair bit of garbage people "reshare" which is pretty annoying at times (you can somewhat easily block the shared-from accounts but they do move around some and people susceptible to getting hooked in liking that sort of thing tend to follow the spam to its new accounts unfortunately).