As someone working on the marketing side of the endeavor, I see the shift the author describes. there are a handful of PaaS companies picking up where Heroku left off and in the enterprise world devops is evolving toward "platform engineering". Platform engineering suffers from being poorly defined, but there appears to be growing demand within large enterprises for something like internal-heroku. But there's still a problem.
To me, the problem is not kubernetes. The problem is that tooling has become so specialized that the focus of work has become integration between tools. And that cumulative integration work complicates the operational responsibilities of software developers. Even if you have a dedicated devops team, the complexity of those integrations flows down to developers in the form of different systems for logging, monitoring, firewall, cdn, ci/cd, secrets, etc.
I haven't looked in a while, but I recall at one time there being a utility that could take a Docker Swarm yaml and convert it to Kubernetes - Kompose? Has that matured into something useful?
There is no good solution here as in order to have a SIMPLE platform, you need to really reduce the amount of use-case you support to a couple options only. The reality is that every single company I have worked for has a ton of different services with different requirements. Those choices end up being reflected on the platform that now needs to be able to run all of them. If you have a single simple use-case then you should just run that simple use-case on a boring EC2 instance with a boring dockerd and a boring NLB in front (as an example) but the reality is that this is almost never the case.
If you have a lot of different workloads to run at scale there is no better tool than Kubernetes. The complexity comes from its power to run almost anything you want