It is not
This looks like a flat object with no heat dissipation properties at all to you?
Your argument would look better if it didnt require to "flat" deny thermophysics for it to work.
Just to be clear, Intel states 4.1w tdp for the Z97 chipset. Even with the red gigabyte logo cover, does it seem like a small heatsink for dissipating that heat output? Now imagine 2.75× that. We even dont know if the 11w tdp figure is just tdp or absolute peak power consumption of x570 under heavy pci-e 4 load
11W TDP is forcibly at full power, it is defined in AMD s methodology as the max power under full usage for worst silicon at 10% higher voltage than what is actually implemented.
Beside the cooler in your pic is the one for a Baytrail that was known to exceed 10W, in this case you can see that the board must be implemented such that the cooler is in vertical position in the direction of its legnth for the air flow to be efficent, but apparently they anticipated that it could be hoizontaly implemented, hence the relatively big size.
Now you can make a test with a device that dissipate 11W and different coolers and aluminium plates...