My team just wrapped a usability study for a website that suffered from content dispersion due to the exact 3 things discussed in this article. People failed to scroll due to large images and whitespace, thinking they'd reached the end of the page...people stopped scrolling because it just took too long...people got frustrated and searched elsewhere for their target content because the pithy blocks of content were too ambiguous and simply not clear enough.
I hadn't attributed it to mobile-first, I honestly don't know if the design team that created the site was following this, but it's a safe bet they were.
It scored high aesthetically, but very low in usability. Form over function creates frustrated, unhappy users for sure, and here is some data to prove it.
Thank you to Kim Salazar, Tim Neusesser, MBA, and Nishi Chitale for writing this up, and Nielsen Norman Group, Jakob Nielsen for supporting it!