The setup can get a bit complex quite early and won't be worth the effort to manage 8 nodes, when you begin to scale to around 20 nodes running a bunch of different workloads (batch jobs, web services, etc.), can avoid provisioning on the application side, etc., then k8s begins to shine more and pay back the investment.
Two clicks to get 1-1000 nodes on GKE. The work is to learn the yaml syntax and the way to deploy to GKE... but most apps need to learn something about how it will be deployed (be it how to use ansible to deploy vs how to setup on k8s vs how to use serverless). But you need to do this for 1-1000 nodes, may as well just do it once...
Kubernetes is more flexible and more powerful, but it's also a lot more complex. You either go with one of the managed distro's which take on some of that complexity but also reduce your flexibility, or you manage the whole thing yourself.
https://platform9.com/blog/kubernetes-docker-swarm-compared/
Edit: updated url to a more recent version of the article