While the product looks awesome, I'm assuming it will be used to cargo cult bad coding questions instead of companies really trying to do something different with their interview process.
When I do phone screens, I generally do two coding questions, plus several other technical questions. The coding questions are a fizz-buzz level warmup question (not fizz-buzz itself, but something fairly trivial that any programmer should be able to do in 5 minutes), plus a more real-world question that requires walking over the filesystem, looking for particular things in particular files.
Beyond that, I do non-coding technical questions that are based on actual problems I've had to solve on the job, and actual technologies that we use every day like standard networking protocols (HTTP, TCP, DNS).
This seems like it would be fairly useful for my coding questions. So far I've done them in Etherpad or Google Docs, and told people not to worry about the precise syntax since that can be hard to do in such a different environment and without being able to run and test your code; then I inspect it manually and look for obvious logic errors. However, something like this would be fairly helpful in letting people write real code and run it.
Many of my best team members weren't people that were so effective at solving computer science problems or even very effective in their editor (I'd actually cringe to watch some of them edit code) but knew when to ask questions of our client or have a theory of mind of our customer in order to know what to build and be able to self-direct.
Conversely, some of my least favorite colleagues would probably fare well in this, but they would tend to rabbit hole creating complex solutions to simple problems or the wrong problem.
Maybe the projects I work on aren't technical enough and overlap with politics too much, but I've never found a gig that wasn't like that.
Obviously this is just a tool and it's up to the companies how to use it, but I think we all know how that will work out.