Right now there is a penalty for not keeping it vacant. Say you’re an elderly homeowner in Los Angeles. Your husband died 15 years ago when the property you bought in 1970 for $35,000 was worth $500,000. The tax basis resets from $35k to $500k. But now the property is worth $2 million and you need to move into a retirement home due to your health. If you sell the house now, your family takes a capital gains tax hit on the $1.5 million of appreciation. If they wait until you die, the tax basis resets to current market value. If you make the qualifying event the move to the retirement home instead of death it would save on taxes but would give your kids a powerful incentive to move you out. Tl;dr most of the vacant homes I’m personally aware of are owned by elderly people with health issues.