Works a lot better than group texts, and with better file sharing to boot. We'll still text each other for 1:1 conversations where we're not near a computer.
We'd switch to Discord if Slack's free offering is ever gimped.
I keep Discord running on my desktop at work, plus I tend to have browser windows connected to it on my both my desktop and laptop at work. I still get phone notifications.
As for using Slack, I am too scared of dropping 3am Friday/Saturday messages in my work chat instead of my group chat so keep separate apps.
Certain programs can keep your computer in a non-idle state indefinitely even if you don't move the mouse.
Having the Slack Linux desktop client open means I don't get any notifications, even when I'm away from my computer.
It is good, but we all have trouble with the notifications. (this has nothing to do with react native but you are here and this is a gripe). Like if you have it running on a computer it doesn't come to your phone. So we have tons of miss-communication for stuff like "yo I am drinking near your house meet-up". Discord just sits running all the time on your PC, which for most is running all the time. So I stopped using it for time sensitive messages which sucks. I would never dare use it for a "Hey I am buzzing outside your house answer". You literally have no idea where the notification for the person is going to go. FB-Messenger never had this issue.