Hm, I'm reviewing my copy of the 2011 NEC and can't find the part I remember. I swore I recall reading something that basically carved out exceptions for thin wires for long strings of lights, but maybe I'm misremembering.

Of course, manufactured items aren't actually regulated under the NEC, but rather UL/ETL or another NRTL. Which is why you run your nice 10gauge wire for a dryer, then at the junction panel inside it switches over to 14 ga stranded or whatever. They've done the math with power dissipation, higher temp insulation, etc etc. And if it burns down your house you get to sue the manufacturer.

As an aside, it's a travesty that public.resource.org no longer has the building codes available. If the codes are not available for all to read, they cannot be considered binding law.