Many a time, especially in a case involving a supposed seller who is either a fake seller or does not actually have the supposed crude in hand yet, or, an unscrupulous aspiring seller's agent or broker who actually has not acquired a crude supplier (seller) yet, buyers may issue an LOI only to find out that there is no seller on the other end. This happens a lot in situations where you have an hungry agent or facilitator who is still struggling to get a real supplier, and by extracting this LOI from an unsuspecting buyer, this facilitator can commit the buyer only for him then to start hustling to find a seller or supplier.
If you are dealing directly with sellers to buy properties, rarely will you need to use a letter of intent. Instead, you'll be meeting with them in person to sit down and discuss options for buying their property. However, if you are working through a real estate agent (or two real estate agents if you're not dealing with the listing agent directly), letters of intent can help you succinctly express your offer in the best light, especially when you don't know if the agent who will be presenting your creative offer will understand the full benefits of it.