Sure, but if you look at the raw transistor count of a series of similarly sized dies (take Apple's A series for example), it holds up. It only doesn't hold up if you look at Intel the last 5 years. If you look at series' made on TSMC or Samsung, it holds up.
If you look at CPU performance relative to density as it has progressed over the last few decades, there's a clear decline in speed improvement. Denser only means faster to a point, regardless of Intel's process update failures.
