I agree that people who pay zero down are upside down due to depreciation as you drive off the lot. However 0% financing and a long term loan is not a bad thing. You pay no interest and as your loan term progresses, the dollar depreciates (inflation) and you are paying off the same principal with ‘cheaper’ dollars.
However, I don’t think there many 0% financing deals anymore due to rising rates (except for maybe huge SUVs that no one wants anymore).