The author made clear multiple times that they were using cron jobs as a test bed for Kubernetes, and they chose to “overengineer” because they’re looking to use Kubernetes for more and more of their needs over time. You’re kind of arguing against a straw man.
I think it’s actually a great example of how Stripe thinks about technology choices.
They’re interested in choosing fewer tools that are better built and can grow to solve more needs. And they’re evaluating tools not just by “time to complete X random project”, but by other longer-term heuristics like maintenance levels. And the best way to do that is to start using the tool for a single need, investing more time in learning/research than is required for the need itself—ensuring that it really is a solid, foundational solution—with the understanding that you’re choosing technology for the long run. Then continue to expand your use of the tool over time, reaping benefits on your initial time investment.