What constitutes substantial?

I assume it's relative to the size of the article.  Pasting four paragraphs of an article that's five paragraphs long is different than if it's twenty paragraphs long.

Also, Fair Use seems to really be about using just enough to get the premise across.  In most cases, that's contained in the first two or three paragraphs.  Of course, "paragraph" is a variable thing.  I just read a Eurogamer article where the writer seems to think that each individual sentence should get its own paragraph.

Going slightly off topic, but it can be difficult to balance the size of "paragraphs" in a news piece or otherwise. Relative to a site's organization, as well as a person's writing style, one sentence may take up three lines, which, for all intents and purposes, can be considered a paragraph. The idea tends to be organizing text in easy to digest chunks though. Instead of presenting people with a wall of nine lines, you can break it down into two or three chunks, even if that means one or all may only have one actual sentence.

It's a fun little game, but deniably, various smaller chunks do look more tempting to read than if you open an article to large wall of text after large wall of text.

Of course, if the writer is just filling one or one and a half lines for each "paragraph", they can go to hell because that's just sloppy formatting.

 a paragraph should be a line of thought,a single argument, etc.  

and 9 lines arent a wall...

Copy and paste with a link.... What the fuck is the problem with that? 

Sounds like you need to get off your high horse.

Says the guy who apparently didn't read the thread and realize that what I see as a problem is already against the rules.

Kudos. Sort of. Not really.