This is not that surprising. First, it depends on how big the YAML files were and what was in them. If you have 200 services, I could easily see 200 YAML files. Second, there are non-service reasons to have YAML files. You might have custom roles, ingresses, volumes, etc. If you do not use something like Helm, you might also have 1 YAML file per environment (not the best idea but it happens).

My suspicion is the original environment (47 Kubernetes clusters, 200 YAML files, unreliable deployments, using 3 clouds, etc.) was not planned out. You probably had multiple teams provisioning infrastructure, half completed projects, and even dead clusters (clusters which were used once but were not destroyed when they were no longer used).

I give the DevOps team in the article a lot of credit for increasing reliability, reducing costs, and increasing efficiency. They did good work.