For one, I often read Dan Piponi[0] / sigfpe's articles on my phone, and they sometimes have long equations that stretch off the page. If you drag the page in the commonsense way, you end up moving to another post, as you say: I've somehow subconsciously learned to drag at an angle and then correct by scrolling up or down as needed. It's sad that it has to be done, but it works.

[0]: Here's a delightful classic with pictures: http://blog.sigfpe.com/2009/05/three-projections-of-doctor-f...