Scrolling is easier than clicking
This observation by Josh seems obvious in hindsight (all the best insights do), but there’s a powerful idea there:
So here is the real difference: scrolling is a continuation; clicking is a decision. Scrolling is simply continuing to do what you’re currently doing, which is typically reading. Clicking, however, is asking the user to consider something new…is this new thing the same as what I’m already doing, or something new?