Why would someone want to use a 'messenger app' at all?
We already have text messages, email and - if you must - Twitter, which each fit different roles in terms of immediacy, audience, message size, and link/attachment flexibility.
What does Facebook Messenger bring to the table? Nothing. The only reason it is installed on so many lower end phones is because SMS isn't always free. If Android had included a built in SMS replacement ala iMessage, Facebook Messenger would have never reached the install base it currently has in those low end phones.
Biting the hand that feeds IT
