Many companies operate at a large scale. If your company or your product doesn't.... That doesn't mean your way is the correct way for anyone.

You haven't caught on that no one has said automation replaces testing or other processes but that seems to be the drum you're banging on. Ansible or whatever tool doesn't replace testing, monitoring, pentests, whatever else you want to do. Automation lets you fix the issues faster and replace servers faster and more reliably, once you have done the testing that you have to do either way.