The part I'd be interested in testing is what happens when the generated site has to handle real business rules, not just look convincing.

Say an HVAC company needs separate service areas, emergency callouts, and quote requests that change depending on the type of job. A generated page might look polished, but if the form sends every lead into the same workflow, or the service-area pages end up with nearly identical content and misleading local claims, the site is already creating problems.

I'd want the builder to generate structured content and working flows, then validate the output: form submission paths, mobile layouts, keyboard accessibility, metadata, and whether location-specific claims are backed by actual business data. Those checks are much harder to fake with a nice preview.

One sentence is a great way to get past the blank page. The real test is whether the result survives the first week of actual customers using it.