When GitHub was young and we were just starting out, we didn't really have anything like this. We had Campfire for internal chat, but not an external IRC like tool for engaging with our early users. The problem with IRC is mostly that nobody used it, it's just not an easy to use platform. We would mostly just use Twitter or something for user conversations.
I remember Leah Culver launching Convore (based on IRC tech) to try to make this easier, but for whatever reason it didn't take off. But somehow, Discord took off and there are _so many_ people there. We opened a server for GitButler and it's been so fantastic for connecting with and supporting our users.
But more importantly, it's amazing to have when you want to engage in a community as a _user_. We started using Planetscale and I had an issue and was able to join their server, ask my question and get a real answer from real PS employees and users almost immediately. Rather than dumping an issue into GitHub and watching it linger. Real time chat is so much more powerful.
Discord has done _so much_ for the open source community. Just look at great projects that embrace it. Go into the ohmyzsh channel and get _anything_ answered, there are like 1000 active users in there all the time.
I just can't imagine the concept of throwing that away because "it's not FOSS".