FWIW the domain is in a smaller font with lower contrast than the title. I would guess that a lot of people automatically skip over the domain when they read hacker news headlines, because it's less legible than the title and feels distinct.
As Kahneman explains in "Thinking Fast and Slow", System 2 (the reflective system, the one we want to be working a little on HN) is lazy and prefers to rely on System 1 (the reflexive one that deals in subsecond responses). I think the protests of HN readers when a title isn't trivially digestible or doesn't quite match expectations are largely the grumbling of System 2 that it needs to get up and move around a bit. And that's actually good for us—not the grumbling, but the working a bit. So the expectation to have titles spell everything out is a mildly bad thing and it's salutary to thwart it a little now and then.