[formerly_proven]

These lower power limits reduce performance a lot on chiplet CPUs (unlike your monolithic APU). The impact is maybe a little less crass on Zen 4 because the 7nm IOD seems to use less power than the old 12nm one used in Zen 2/3.

For example, a 5600X in CB R20

   PPT   Freq      Points (nT)  Core power
   82 W  4500 MHz  4350         54 W         (stock)
   65 W  4200 MHz  4000         43 W
   38 W  2500 MHz  2400         17 W         (lowest allowed)

The SoC/uncore consumes around 15-20 W on Zen 2/3, so at 38 W you only leave 15-20 W for the actual CPU part of the CPU. Meanwhile the low-load and idle savings are essentially nil because all of the idle power is the IOD/uncore.