well, there are some reasons for [1][2], it also was on HN before too [3].
I came up to it as i was looking for an alternate which is free, real end-to-end encryption (not just to the server) and doesn't need your or any phone number to create an account.
There is a payed Version (obviously for professional occasions) and also a Desktop Version. So all in all a great Package. I suppose it makes money through it payed Version. (havn't checked that, just assume it) It promisses not to steal data and says its not possible by design.[4]
Sometimes, i don't even understand my closest friends. This should not be anything you need to tell anyone...