What if they literally destroy the place?

If you read it back then and asked some questions, I'm sure it would not have destroyed your REI confidence.

Between stamp duty and capital gains tax here in Australia it destroys property liquidity and that makes it actually harder for people to get into the housing market - be they young (first home), upsizing (growing families) or down sizing (elderly).You need to not impede volume and liquidity, we’re living the other side.

Your tenant destroys house and you only make a few hundred a month on the house.

https://www.whio.com/news/loca...There is another article in which it mentions about the abandoned homes will be destroyed and land will be sold to investors or some will be turn in to parks.

I disagree, this will spill into the RE market and will destroy the commercial real estate market.

The forums are actually full of posts, if you look for them, from investors in high cost markets who bought a random property in the midwest and then discovered it needed tens of thousands of dollars in capex, destroying the cash flow for years. 

I have seen a state or two that has laws on the book, for a criminal offense, if i a tenant intentionally destroys a landlords property.

Low income tenants destroying dishwashers is not a rare event.

To answer your question: Yes, the vapor retarder will stop most moisture from the ground from destroying your joists and rotting them out.