It's a bit hand-wavey logic in the OP. He's saying the cost of a home should be affordable, therefore any intrinsic value of the land (versus the cost of building the structure) should be taxed very heavily, such that 100% of the value of housing spending goes into the structure and not the land. Land is merely a vehicle to produce tax revenue, if anyone has extra land, they must pay for the privilege.

This would be disastrous for our house, we have a large wooded plot, it would presumably be heavily taxed beyond our means to pay.