I find your answer to be contradictory. In simple terms, what would prevent Zen3 from running all cores at 5GHz, from the 5600x to the 5950x? Short answer, POWER!
That means Zen3 will simply stop scaling with power at a certain point beyond 4GHz, while GC will blow past 5GHz with ease. So how can you claim efficiency for Zen 3 "at all frequencies."?
As you've aptly stated, Intel's willingness to tap into higher wattage for higher frequencies is deliberate. It simply is a strategy of fighting many 'slower' cores with less fewer cores. Operating at such high frequencies comes with a certain sacrifice of efficiency. If we understand this going forward, then we'll not be making blanket statements when we very well know Zen3 is not even capable of playing in that 5.3GHz without exotic cooling.
If we look at the power comparison between Zen3 and Tigerlake by Anandtech, I believe WC maintained linear efficiency scaling beyond 90w and showed no sign of waning off. Zen3, on the other hand, could only maintain linear scaling up to around 70-75w iirc, so that by around the 90w mark, it had gradually dipped to the same level as WC. Meaning, from that point forward, WC was going to demonstrate better efficiency over Zen3.
As
@Accord99 has indicated, the GC chip to demonstrate the best efficiency capabilities of the GC arch is the i5 12400, with 6c/12t just like the 5600x. Preliminary results show it's beating the 5600x with same cores and threads clocked a tad lower, and using less energy to do so. So, I'm looking forward to all the reviews and praying Intel throws a surprise 12400 in the mix just to highlight this point. In any case, the 12600k is not aggressively clocked like the 12900k, so maybe we'll see some glimpses of GC efficiency with the less aggressively clocked chips.