Imagine how much hotter if they hadn't built a vapor chamber? It appears almost all vendors have gone too far down the path of "thin" for the gaming segment at least. Sooner or later vendors may well realize that a bit thicker and heavier isn't bad if cooler and quieter are the result. And going to desktop chips simply offsets the "thicker" with "hotter" which doesn't improve things really.
Ryzen chips are still not plentiful in the supply chain but yep, definitely cooler. The limits on pci-e lanes however would hurt a full high end gaming design. That will change when Ryzen mobile can manage pci-e 4.0 but that, also seems a bit of a ways off. So not all design choices for Ryzen are perfect either.
I wonder if testing should include a session of disabling hyper threading. On desktops the 9700 was a vastly cooler chip than the 9900 and yet in games it was pretty nearly the same speed. You'd probably improve battery life as well. And since undervolting doesn't work in every situation but turning off HT does, it might make a more universal heat reduction technique that can be used by anyone.