You're talking about modern geometry. They call it 'compact geometry', because the tendency is to have a shorter seat tube, relative to the top tube and rest of the geometry, and the top tube sloping down. With this geo, the idea is to have a fair bit of seatpost sticking out.
I was talking about proper road bikes with horizontal top tubes, and frames made out of steel However, my carbon Orbea was 56cm, and I was fitted for that properly.
The impression I get from the first post is that he's talking about an older stye, steel bike.