Seems very relevant to many existing SaaS services today: 1. They are not doing CD, but they do deploy frequently. 2. They are using K8s, or even immutable infrastructure, so far as I can tell. 3. They have a lot of people involved in maintaining their deployments system. 4. Speaking as a user, I do not recall many significant outages, so on the surface, it seems that they have sufficient reliability.

Speaking as a heavy user of Kubernetes, evolving from an existing VM-based application to something like what Slack is doing seems like it might be more sensible than a "move everything to microservices and Kubernetes" modernization strategy.