> a common-sense mental model for web development.

You are contradicting yourself. Either its a "minefield...of edge cases..." Or it's a common-sense model. Not both.

I'm convinced we're still in this minefield of edge cases, not in a situation where we've solved all this, and where the tech to build "frontend" is clean, predictable, free of historical baggage etc etc etc.

All we have done, is plaster over these foundational mistakes and invcompatibilities. We haven't solved them. React doesn't solve the fact HTML was never designed to be a UI toolkit. Next.js doesn't solve the fact that JavaScript is full of design mistakes that prohibit it from ever becoming a safe, sane, reasonable (literally) language. Tailwind doesn't solve the problem of CSS being haphazardly introduced to style a markup which was never designed to be styled. Etc.

All LLMs now do, is having the "knowledge" of the horrors under the plaster, in a statistical model that was trained on examples from an era where 99% of the examples are hardly more than plastering to fix the ever reappearing cracks in the previous layers of plaster.

No, they are saying that the frameworks and tools discussed in TFA have made it look coherent. For the most part we have not worried about compatibility for a decade. All abstractions leak a bit but in practice it holds up quite well, well worth the cost savings and flexibility for many apps.