Arduino Uno with a 32-bit ARM Cortex-M0 in 28 pin DIL package

That kind of comparison makes sense if all you do with your mcu is to add 32-bit numbers.
Even in that comparison, what if you wanted to process char or short?

More importantly, for those of us using those chips for a variety of different tasks, you would be hard-pressed to show the cmx chips are 10x faster than a comparable avr (or any other 8-bit mcu).