The rule changed shape
Everyone scrolls, so cramming every important thing into the first screen is obsolete advice. What has not changed is that the first screen decides whether scrolling happens at all.
The first screen has one job
Establish what this is and who it is for, clearly enough that a stranger continues. That is a single job, which is why one action and one idea matters most here.
You’re no longer trying to fit everything above the fold. You’re trying to earn the scroll.
It’s smaller than your design shows
On a phone, browser chrome, a sticky header and a consent banner can leave a fraction of the viewport. Check what genuinely remains on a real device before deciding what fits.
Don’t make the hero an obstacle
Full-height hero sections that push all content below the first screen force a scroll before anything informative appears. That is the modern version of the old mistake, with better typography.
Speed is part of the first impression
A first screen that renders slowly is not a first screen. This is where server-rendered HTML and correctly sized images pay off most visibly, because it is the moment being measured.
The signal to watch
Scroll depth on your key pages tells you whether the first screen is working. If most visitors never pass it, the problem is up there — not in the sections nobody reached.