Well, I guess to be fair. Windows 8 styling is something that you could do in CSS (and is done in CSS for some apps), so HTML5 apps will look native (to Metro).
Hell, looking at Safari, I see no reason why you couldn't put together an interface like this in HTML/CSS. To the grandparent's point about Java Swing, I don't have much experience with Swing, but I did see a little as I was entering college in 2003 and it objectively sucked. And that was 4 years after the hypothetical article title presented. I think the biggest thing hindering the HTML/CSS thing on certain occasions is performance, and even there, browser performance is pretty damn good these days.
Edit: My last sentence may or may not have somewhat proved what the grand parent was trying to say.
We'll see what happens to browser performance when most apps on the Win8 desktop are HTML/JS/CSS based and when typical displays have 300-400dpi... We'd probably get better performance if we resurrected NeWS.
300-400 dpi on desktops is a silly idea. 200 dpi is excessive for a display that sits a couple feet away from you. Even for laptops which have screens that are on average closer, 200 dpi is pretty much all you need. Going much beyond that gets you very little in terms of perceived quality while costing a lot more to manufacture.
Edit: My last sentence may or may not have somewhat proved what the grand parent was trying to say.