I thought that technically the LL then owes the IRS in imputed income? (Income based on market-rate rental values)?
It is similar to person A borrows from a person B $10,000. B pays back $100. Person B decides that A is a deadbeat and declares $9,900 a loss. Since B no longer needs to repay $9,900 the $9,900 becomes income to A. B sticks A with a 1099 for $9,900. Now A needs to pay taxes to the IRS on $9,900 that he got from B.