Please stop the coding challenges

> build a mini-app from scratch in just a few hours

It depends on what kind of functionality we're talking about, but this kind of task is exactly what people at my current startup have been assigned at times. It is absolutely possible to build a CRUD web app with reactive UI using modern tools in a few hours.

> This is like asking a Ruby developer to debug PHP as a test of flexibility

Again it depends on what the debugging task is. At every startup I've worked at, it's expected that an engineer is able to jump into a task that they know very little about. Granted it becomes less reasonable the more niche the task, but PHP and Ruby are not particularly far apart in skillsets in the grand scheme of things. I would expect any web engineer to be able to do this.

> Hiring processes should focus on problem-solving, collaboration, and growth in relevant areas

I agree with this. And, hiring should also focus on technical ability which does include working through difficult and unknown problems by oneself.

> build a mini-app from scratch in just a few hours

But how often do devs normally set up a project from scratch? We have like 3 new apps in a few years where I work now in addition to the long running ones. So on average one in like hundred devs here have been part of creating something from scratch.

Sure, when you know what you're doing it's quick. But the first time can be slow, no matter how good you are. So for a coding task that should take a few hours, you might have spent all the time just getting up and running, and then you actually start the task as over time.

> is absolutely possible to build a CRUD web app with reactive UI using modern tools in a few hours.

Yes, but it also leads to tons of bikeshedding. "Should I implement a linter? Should I write unit tests? Integration tests? Should I mock HTTP calls or use a mock server? How should I deploy things? How do I structure my CI?" All these choices are extremely subjective and context dependent and then somebody's gonna pass on you because they don't like that you used Cucumber.

Setting up a project is not something you do often, and if you do, you probably have templates and some team standards.

It's much better to give somebody a project structure and ask them to implement some basic task in it.