SOA -> API as PaaS -> Docker
I frequently make an analogy of why API's have supplanted SOA as being for similar reasons why Docker/Kubernetes is supplanting PaaS.
SOA was architecturally superior and theoretically provided the same benefits as API's. Many companies went down the SOA road but few ever implemented it very far. For instance, governance registry is pretty key part of the whole reuse idea in SOA and those were rarely implemented by companies and those that implemented them rarely found much reuse. Reuse which was a primary goal of SOA and it was never achieved in most companies.