I'm not sure you actually disagreed with the parent.
The parent said something like "there's not enough demand, and too much supply". You said something like "it's very expensive to produce good journalism". The two statements are not contradictory.
I do agree with you that there is a definite problem with the current situation, by the way.
There's very little demand for high quality journalism.
A high quality article might cost 100 times as much to create as a low-quality one, but the returns from it (ads, subscriptions, whatever) aren't anywhere near 100x as much. At this point, all magazines, newspapers and similar outlets have figured this out.
There may be some sort of niche possible in ebooks aimed at relatively narrow niches - niches that aren't served by general interest publications. But for regular old publishing/"journamalism"/opinion pieces.... the outlook for making a living at those is not good.
I think our attention disorder deficit world (1) and the lack of transparency (2) lead to just that: Lack of demand for high quality journalism.
(1) Quality journalism usually demands time and attention from the reader since it presents itself in multi-page articles that try to distill down to the important facts. Oftentimes reality is so complex, that even this distilled view is difficult to read and takes some time to understand. People who just want to read some news between checking facebook or tweeting are not interested in these long and elaborate articles.
(2) Even for short articles, it is difficult to assess the quality of it since there's no way (or only a difficult way) of figuring out whether an article is high quality or low quality. In order to find out, you'd need to be an expert in the specific domain or re-do the work of the journalist (fact checking, etc). Since most readers neither can do the one or the other, for a normal reader this lack of transparency (or information asymmetry, as the economists say) means that he doesn't see the difference between high and low quality. So there's little demand, too.
I do think that there'll be a future where high quality journalism is flourishing, but not with the current business models, and not with the current way of news publishing. My hope is that at some point a startup will figure out the correct ingredients (and I doubt social news, or anything in that domain is the answer)
The parent said something like "there's not enough demand, and too much supply". You said something like "it's very expensive to produce good journalism". The two statements are not contradictory.
I do agree with you that there is a definite problem with the current situation, by the way.