Because the root comment is mostly but not quite right: there are indeed a large subset of developers that aren't interested in thinking about infrastructure, but there are many subcategories of those people, and many of them aren't fly.io customers. A large number of people who are in that category aren't happy to let someone else handle their infra. They're not interested in infra in the sense that they don't believe it should be more complicated than "start process on Linux box and set up firewall and log rotation".

For some applications these people are absolutely right, but they've persuaded themselves that that means it's the best way to handle all use cases, which makes them see Kubernetes as way more complex than is necessary, rather than as a roll-your-own ECS for those who would otherwise truly need a cloud provider.