For most static UI surfaces, I probably wouldn't use it, but I can see a use case in this for testing generative UI workloads.

Sure, server-side or client-side generated UIs tend to have a lot more interesting complexity to test. But I do want to bring up that with the specification language being TypeScript, you can validate some basic properties even for statically generated sites. I wrote a spell checker for Bombadil that uses https://github.com/wooorm/nspell and a custom dictionary and found a bunch of old typos on my own blog.