Air Conditioning - How can A/C zones be ok?

I believe it's generally accepted that you should never close supply registers to direct air conditioning to only certain parts of your house.

But I see fancy zone controllers for sale all over the place which make use of motorized dampers, which as I see it would be the exact same thing. Perhaps even worse, from an air restriction standpoint.

What gives?

If a home has a zone damper put in, there maybe a few things done.

-Supply duct temp sensor. It sense temp in the ductwork if it's too hot or too cold, it will turn off the burner or outdoor unit to prevent over heating or frozen coil.
-By pass damper. If the pressure build is too great for a zone, there is a damper that opens and dumps the extra air flow back in to the return, or a basement zone.

-Ductwork sizing. The main duct that is going to a zone maybe sized larger than a duct that maybe doing the whole house at once.