I hate slack and chat in general being temporary at basically everywhere I have worked. So often a colleague will give you instructions on some process then the next time you need it, it's gone.
When the company moved to Teams (because it was free with the other Microsoft stuff), I asked if it would be possible to get an archive saved somewhere and I got the brush-off, "we'll look into it". It's a shame how much was just thrown out.
Oh well. Time for the industry to move on.
If you're not paying, it's not a sale.