It's 2025 so I blogged again, this time about remote work: https://blog.tadzik.net/the-importance-of-offtopic.html
@tadzik@social.tadzik.net Nice blog post!
At my current job we (sadly) use Slack as well, and the same issue exists. We have management-approved off-topic channels, and they're all as dead as can be. Rarely someone will share a link to a youtube video and will get no replies whatsoever.
I made a private channel for my team, with nobody from management, so we can speak privately and talk off-topic without fear of managers seeing it as "slacking off", which appears to have a very positive impact on socialization inside my team, at least.