Earlier quoted context omitted.
Even though I use it a lot for 1 on 1 convos it's definitely not eating that lunch (yet). And imo it won't as long as it remains less reliable for notifications and doesn't have things like last-online, quote replies and read receipts like messenger and WhatsApp.
I don't understand why read reciepts are important. People will respond when they feel like whether it says read or not. Just makes it more cumbersome to get around it when you're too busy to respond.
It avoids the whole "hey, did you get my text" thing and there's several social situations where knowing whether the other person has read your message (regardless of reply) is useful, so you don't end up calling them to do exactly that.
It's like quote replies, emoji, etc… none of these things are essential to 1-on-1 comm, but if there's a platform that has these features, it'll most likely win out over others.