Google would be catastrophic because so much is stored there.
Slack is mostly real time communication, at least for me. There are a few bits and bobs that really should be documented that are in the messages though.
Yeah, Google would easily top the list of companies which can have catastrophic impact. Microsoft, Apple, Salesforce, Dropbox would be the next in the list I guess if we leave out the utility companies and internet providers etc.
Just look at the impact a 40 minute outage of Google Auth had last month, I wouldn't be surprised if the global productivity hit during that outage was in the billions of dollars, and that was for a relatively short outage without any data loss.
AWS outages have basically crippled a few businesses. The longest I know of was 8-10 hours the day before Thanksgiving. Some Bay Area food company got hit by it and couldn’t deliver thanksgiving dinners.
Slack is mostly real time communication, at least for me. There are a few bits and bobs that really should be documented that are in the messages though.