But Kubernetes is solving a much messier and more complicated problem than React. There are numerous similar web frameworks to React in different languages that have been created as basically hobby projects.
Of course Kubernetes is going to be way less fun to use. The problem of managing servers and distributed applications at scale is inherently not fun once you get into the nitty gritty details.
Kubernetes has the basic flaw that it has more scalability than 99.99% of companies need and you could serve almost all the market with a system that supports shared data structures (like IBM's Sysplex) and is more opinionated. An architecture which is less scalable could serve almost all of the systems on the planet and would be easier to work with.
I'll grant that there is essential complexity there, but Kube was built by people who didn't have fear of accidental complexity so it has a lot of it. Look at the whole "YAML sucks" thing which is partially a YAML thing (coulda chose something different) and also a function of the system they are trying to configure with YAML.
Kubernetes' YAML problem stems from its CLI tooling, and yes it was an atrocious choice once templating came in and visited horrors like helm on us. Internally, the the k8s api speaks only JSON, and you can already stuff whatever json you like in a yaml file.
Of course Kubernetes is going to be way less fun to use. The problem of managing servers and distributed applications at scale is inherently not fun once you get into the nitty gritty details.