Disclaimer: I work at Google. IRC is still actively used as a main communication channel internally at Google to coordinate during outages due to its reliable

Disclaimer: I work at Google. IRC is still actively used as a main communication channel internally at Google to coordinate during outages due to its reliable and low-dependency nature (where a Slack equivalent app relies on hundreds of service dependencies). I know for a fact that Google is not the only company, and many others that practice SRE-like roles do the same.