I imagine the idea behind this was to avoid having to roll an in-browser IDE with the advantage of letting users use (and learn) the actual tooling that comes with that language.
I personally liked using my own editor, but the CLI didn't provide much added value in my opinion. The tests were enough for me and it was kind of annoying to have to run the CLI every time you're finished just to get the next exercise...
Yes, but what's the value in this website having a dedicated application that I either have to trust blindly or evaluate and compile?
We already have this great sandboxed environment called a browser for running untrusted code from the internet. They could still offer endpoints for curl, if it's just about using the command line.
It was originally designed as more of a mentoring platform, so you would be led through it by a friend that knows the process. It's easier to trust a friend than a code review for a non programmer. It's also easier on the friend to be able to download just one binary and start mentoring than for her to have to find a bunch of requirements just to get the exercise.
It's enough to have to get all of the language's requirements installed...
Yeah. But reviewing 1900 lines of code before I've even seen a single one of their exercises? That doesn't sound like fun. I would be far more willing to run their app if I could try the actual service first.
It's not absurd to have a healthy distrust of foreign code running on personal machines, especially binaries from random people with a website while there's no discernible reason for a binary in the first place.