Pushstate and Infinite Scrolling Article Pages: Is it detrimental to not change URLs as the page is being scrolled?

[Cox-Media-Group]

I've noticed a recent trend of news sites using infinite scrolling on article pages to garner more pageviews and I can assume serve up more ads. Here is an overview.

Here is an article from NBC news that uses this technique:

http://www.nbcnews.com/pop-culture/music/grammys-2016-here-s-why-adele-s-performance-was-out-n519186

Studies have shown that this technique has decreased bounce rates by +15% for some sites.

My question is: If a site is using the technique without changing URLs as the user scrolls down what overall negative effects does this have? Obviously you wouldn't be getting credit for the extra pageviews but I was wondering if there were any indexation implications with this.

Here is an example of article infinite scrolling without changing the URL:

http://www.wftv.com/news/national-content/deputies-wife-attacks-husband-because-he-didnt-get-her-a-valentines-day-gift/87691927

[JordanLowry]

The parallax or infinite scroll effect is going to cause some SEO issues since it is basically one webpage with a single url. This is going to make it difficult to optimize your site for a variety of search terms and could lead to keyword dilution since you are optimizing only a single page.

Also, I would imagine an infinite scroll/parallax site would present some analytics issues as well. One issue I have noticed with some client accounts that I have put heatmaps on is no one scrolls below the fold. So I would imagine having a single infinite scroll site design you would see higher bounce rates. I have seen some sites, however, use their homepage as a parallax scrolling page with specific content pieces linked throughout the homepage.

Google has provided some insight into infinite scroll pages on their official webmasters blog which can give you some more insight.