You do if you need the risk adjusted return and can’t get it elsewhere.

You should read more on seller/owner financing to understand why one would use it in a transaction before dismissing it as a scam. To think only scammers would benefit is an ignorant position to hold if you don't understand why counterparties in a real estate transaction would elect this financing mechanism over conventional financing. Ownership interest is still recorded with the local jurisdiction, so nothing is hidden (although with a land trust, you can hide beneficial interest [it's treated as personal property and handled with trust docs; you could think of it as tracking real estate ownership "off ledger" since it's not recorded with a deed] so people don't know who own a parcel).