Why does it matter to me if all of slack goes down at once? I only interact with "my" slack. There is no material difference to my team's experience if "all of

Why does it matter to me if all of slack goes down at once? I only interact with "my" slack. There is no material difference to my team's experience if "all of slack" goes down vs "our standalone chat server" goes down. The only relevant issue is whether or not Slack's team creates a more reliable service than my poorly maintained homegrown solution.