I wonder how widespread the adoption of steam deck + clones has been amongst benchmark participants (very very good perf per watt, relatively middling absolute performance), that could explain a lot. Not sure where they would end up on the desktop vs laptop categorization.
For a little while before that, CPU performance was stagnant with Intel on top until AMD released Ryzen and Zen, and Intel got stuck on 14nm for half a decade. Suddenly AMD is posting substantial performance improvements every cycle and Intel is cranking up TDP to compete. Now we have competitive x86 processors from two different sources AND competitive ARM processors from two others.
The companies that don’t buy out the first year-or-whatever of capacity on new nodes should still get the same year-over-year advancement, though. Just, with a small but constant delay.