Thanks for providing those numbers. Pretty much what i expected
My guess is, that those 5-6W on idle that gets thrown around in so many blog posts is probably just the CPU in idle state and not the whole board with io and other stuff.
As i said. The RPi (and other SBC) remains king for low power and low load applications like for example smart home. Especially in counties like germany with high energy prices. But honestly i am always surprised what can be run off a RPi.
And i just looked. The price for a RPi is actually not.that bad anymore, just saw a ebay listing for 3 * 3B+ for 100€.
For other low power usage where arm is not feasible those intel embedded based thin clients are an excellent choice.