That is false in the case of a house. a house you live n can lose value relative to inflation and still be a good investment. remember you have to live someplace and so that rent cost needs to be subtracted from you total investment costs as you would pay it anyway. After you pay the house off (if you do) you continue to sbtract those costs from your investment.

a stock or bond might have a better return but a house also diversifies risk and so is a good investment for that.

the above doesn't mean a house is good for everyone. Just that the analisys everyone else is doing is missing critical details.