You're ignoring what was written: if the building has value 0, then it is not maintained to keep the value up. Of you kept the value up, then it would not have an effective price of 0.

Of course most people put money into properties exactly to keep value up.

>also writing off all of those expenses

Writing off expenses does not make them free - you are still paying for them - out of otherwise profit. It just means you get taxed on net profit instead of taxed on property gross income. But you are still losing money.

Writing off expenses is not some free money giveaway.

The point was to illustrate that OP ignored costs involved for landlords in the thought experiment.