I do agree that the article would be better on several pages, however I have come across some very long one-page articles that were well worth the read. Still, long articles are less likely to be read than shorter ones.
Go find something long in the Web and begin reading it, paying attention to what your eyes and hands are doing as you read. Here's what the experts say...
Before you being reading, your eye is going to canvas the screen for something of interest. Now, this canvas is 'above the fold', so if the reader must scroll to access the meat of your content, you may well lose the reader before he/she ever finds that point that would draw his focus and pique his interest in what you have to say.
You'll find that white space is critical in keeping your attention as you read. Yet, the more white space the writer uses, the less area he has available for content 'above the fold'.
As you read down the page, notice what your hand is doing. Its probably scrolling the page as you read. A lot of 'gurus' will tell you that website visitors have poor attention spans. That's bullpuckey!
What happens is that when reading on the screen, your eye finds its point of interest and fixes on that point of interest, reading while you use your mouse or keyboard to scroll the page, helping you maintain your interest and at the same time searching for the next point of interest to draw your attention.
That's what the experts mean when they tell you that Internet readers scan a page. There's more to it than that, but reading while scrolling is a part of it.
Finally, if you are using a mouse as you read, notice your urge to click while reading long content. How many times have you right-clicked unintentionally or clicked a link that you really didn't mean to click? Of course, clicking takes your focus away and then you must begin the process of finding a point of interest again.
There's so much more to say on this subject that I could well turn this into a 3000 word article, but then how many of you would read to the bottom? So I'll just leave you with these reasons why longer articles can be wonderful but they are best split into several pages.