More like there are things wrong with the marketing, much of it further perpetuated by the magazine writers and internet.
Lets start the AFR meter. It doesn't read AFR. It is an interpretation of AFR based on oxygen in the exhaust. In any engine, but particularly a hopped up engine, the products of combustion at idle can fall outside that interpretation. A CO meter is better at idle. If you are interested I can post up some links which get a lot more into this. Both some on why what is in the exhaust pipe may not be what happened inside the cylinder, and how the products of combustion themselves can be different than expected because the components did not burn in a 'normal' manner.
Rich or lean at idle. The whole 'lean idle' thing is to reduce amount of unburned hydrocarbons and CO. You don't have to beleive me, read the Chrysler Master tech booklets about carburetion from mid 60s to '70. They, as do the shop manuals, explicitly explain that to reduce emissions at idle the idle mixtures will be run leaner. That instead of using the old methods, adjustment of the idle mixtures must be tuned to as lean as 14.2:1.
Further, the idea of running somewhat richer mixtures at idle for best economy is not just a 'it worked for me - it must work for you' theory. It comes from the scientific and engineering community (academic, industrial and military). There has been extensive testing of engines in laboratories and in the field which can be read in several textbooks and published papers.
