Earlier quoted context omitted.
Having been on IRC for maybe two decades now, I find the impermanence to be part of IRC's charm. People engage with you when you ask them what has been going on; just like in real life. It's a social protocol.
Certain use cases that Slack et al cater to, you might not get to choose impermanence. There might be compliance/regulatory issues that require you to have document retention policies.
I did change careers to escape that...