Also in principle there is end-to-end encryption, which is not a reason I switched. I'm not sure if this feature has been there when the 200k crypto contest went up with its criticism, but in principle it should be completely dependent on the client, which is opensource.
Too bad XMPP/Jabber did not get a breakthrough, what is the reason for that? No user friendly client? Noone putting enough advertising into it; you can't make money with it?
In germany there is currently a hype of Threema. Every magazine and newspaper writes about it being secure with end-to-end encryption. Even IT magazines just write naively about it, ignoring completely that it's closed source and noone can even see slightly behind the curtains.
I rather prefer to see/know the flaws (Telegram) than use a proprietary solution that makes the masses "feel" good. See also: https://news.ycombinator.com/item?id=7281338 Even that Threema costs some money makes people more confident of its security, with the reasoning that with a free solution you are not a customer but rather the product and you pay with your data.