I've frequently heard users complain that they'll be reading the main content of a page (such as a news article) and an image or other content will finish loading above their current scroll position. In the current behavior, this pushes the content down, jarring the UX. The users I've heard from report this as a major annoyance.

Instead, perhaps we should take a reasonable guess at what is the "main" content of the page, and anchor the scroll position to that. Then when the page shifts, the main content stays in the same position in the viewport.