The author's answer to this question is totally wrong.
> Either way, expect no HyperCard (or work-alikes) from Apple. But how about other vendors? What about open-source projects? Nothing there, either. Oh, there is no shortage of attempts. And all of them are failures for the same reason: they insist on being more capable, more complexity-laden than HyperCard. And thus, none of them can readily substitute for it.
Really? Nobody ever had the intelligence and discipline to design a simple GUI builder in the history of computing since Hypercard?
No, the answer is that there are numerous simple GUI builders, including GUI builders for the web. But none of them are popular, due to the sweet spot of supply and demand that Hypercard hit.
When Hypercard launched, it came with every Mac, it was free, and there was nothing else like it available on the Mac. On the Mac, the alternative to Hypercard was to layout UI widgets in code, with no GUI builder at all, or eventually to pay $$$ for a professional-grade IDE like CodeWarrior. As an entry-level user with no budget, if you wanted a GUI builder for the Mac, you got Hypercard, or nothing. This created a community of Hypercard enthusiasts.
Furthermore, when Hypercard launched, Macs had a standard screen resolution. Every Mac sold had a screen resolution of 512x342 pixels, so you could know for sure how your cards would look on any Mac. Supporting resizable GUIs is one of the hardest things to do in any GUI builder. (How should the buttons layout when the screen gets very small, like a phone? Or very wide, like a 16:9 monitor?) Today, Xcode uses a sophisticated constraint solver / theorem prover to allow developers to build resizable UIs in a GUI; it works pretty well, I think, but it's never going to be as easy to learn as "drag the button onto the screen and it's going to look exactly like that everywhere."
The last issue is the real killer for modern Hypercard wannabes: it's a small step from a web GUI builder to raw HTML/CSS. You don't have to pay big bucks to have access to professional-grade HTML, CSS, and JavaScript. Sure, they're not that easy to learn, but you can teach a kid to write interactive web pages, no problem.
As a result, the demand for a simple GUI builder is lower than it was for Hypercard, and even when you do capture a user, they tend to outgrow your product, and there are a zillion competitors, so none of them can build a community with real traction.