For some reason I feel like I have become some sort of FB defender, but I am not. Just to be clear, I am not a fan of FB. I even completely got rid of my FB account a year ago because I got sick of fake interactions on the site and have never looked back. I am happy with communicating with close people just via text and other special purpose communication apps.

That said, the reasons you mention are pretty edge cases. Instead of just hating on it, just stop and think about it for a moment without prejudice. When you email someone you don't expect them to read it immediately, but when you send a text you at least expect them to know they received something, no? (If you say no to this, I really have nothing else to say anymore, you would be just denying the reality) That's what Facebook wants to be. They're competing with SMS, not email.