At the same time though, if it's structured as a "rent to buy" the buyer is exposed to huge counterparty risk on the part of the "seller". If anyone senior to them, including the county in the case of property tax, forecloses on the house they end up with nothing but an unsecured claim even if they're 2 months from paying the entire amount. Even if it is a real recorded mortgage, the seller is getting significantly above market interest on what they deem to be a low risk, so their risk adjusted return is pretty high. This is like being able to sell a call option on the S&P 500 for 50% more than the going rate.
Sold a California non-residental property for a significant gain. The buyer requested seller financing. After realizing I could get tax benefits using the installment method, I was eager to do the financing. Was not looking to reinvest proceeds so no 1031 tax deferred exchange for me.