Doing one thing well is not a winning advice. You can do multiple things, it really depends on the execution and other factors. They are doing one that is workflows and doing it well.
Like GitHub Actions is a workflow, but it's a convoluted YAML wrapper around shell scripts.
Is a workflow shell scripts? I'm going to guess no. I'm going to guess it's "code". So... why is a workflow code but code isn't a workflow?
Windmill is a "workflow (code?)" orchestrator?
But i do agree that windmill is doing so many things that the elevator pitch need some work. But a lot of companies are trying to do the same. So i do not think people will think of workflow engine + online ide + app builder as a natural grouping in 5 years