Great post.
It's sad that most of today's users are not concerned at all about the security of their information, specially their messaging apps.
No wonder the most widely used have very weak or no security at all (Whatsapp, Viber, Messenger, Skype, among others).
Hopefully one day however people start realizing how important this is and start doing something about it ; and that's something that won't be happening any time soon - or so I believe.
To be clear, What'sapp and others often have strong security, but bad privacy. You should assume Facebook is reading and recording everything you send on What'sapp, even if random Internet hacker can't, because Facebook makes What'sapp, so when you use it, they control your data before and after it gets secured.
"others often have strong security, but bad privacy" is such a concise way to refer to the problem with this type of outlook.
Following as of now...
I couldn't have said it better!