DevOps talks about automation in development. version control, open source, inner source, automated build, automated testing, release processes and so on. Still it is important to include your production in your DevOps.
I would say that testing in production is the only way to improve quality, since errors hit you in unexpected ways and with great and unforeseen impact. As a fact: • Changes are implemented all the time in servers, network, applications, databases, SAN and so on. • All changes are implemented with the best intentions but in a world of microservices no one can foresee the full impact • No matter how much DevOps you have implemented in your development processes, these changes may influence response time and availability in ways you would never imagine The only way to really have a continuous improvement process that is worth the name is to monitor your production. All systems, all users and all the time.