Imagine you want to deploy some microservices to Kubernetes. You can just create EKS/AKS/GKE cluster from the GUI, `kubectl apply` a few resources and create a load balancer to point your domain there. That will work. But...

You probably want to automate the infra creation (so Terraform, Pulumi, CDK...), you want to automate building (so GitHub Actions, Jenkins, Bitbucket Pipelines, GitLab CI...) and artifact storage (so Nexus, Arti, ECR, GHCR...), you want to automate deployment (so Argo, Flux, Helm, Kustomize...), you want to automate monitoring (so Prom stack, Datadog, many APMs, Splunk, Graylog, ELK... could easily name a dozen more).

Each part of the stack can easily bring a dozen different tools. I work in SRE and I use at least 40-50 tools for a mid-sized project. And this is "normal" :)