You cannot compare an open chat, with a strong interest in a particular topic vs you team's Slack channel.
Online games work well, because you have a visual and full engagement.
Compare that to work communications... You are totally async on slack, it's just a simpler version of email at this point. Just because people are online in Slack today, doesn't mean that they'll respond within minutes.
If someone is online playing a game, you know that they're there. Old IRC was pretty much the same.
I get what you are saying but I seem to find it hard to engage with anyone, even my old friends, over chat these days. We end up hopping into voice chat when we want to catch up.
Online games work well, because you have a visual and full engagement.
Compare that to work communications... You are totally async on slack, it's just a simpler version of email at this point. Just because people are online in Slack today, doesn't mean that they'll respond within minutes.
If someone is online playing a game, you know that they're there. Old IRC was pretty much the same.