Can we talk about "center bore" for a minute?

I have balanced many tires and rims. The hubcentric is not nearly as close as they should be. U can see by the naked eye that they move up and down. The new way to balance rims and tires is to have a 4,5,6,7,8,10 lug adapter. U are balancing off the lugs instead of off the Center of the rim. Kim