Contingencies _ The buyer's offer is contingent upon certain keys facts being confirmed. One example may be confirming that the current lease is transferable to the new owner. Also, their willingness to buy is contingent upon the due diligence period confirming that everything you have stated about the business is true.
So, if a letter or document that nominally or presumably conveys the signer's "intent" or intention to buy, is essentially meaningless and worthless in legal terms, and is not binding on the signer or anyone, and CANNOT be enforced on him, then why would a respectable crude buyer, in the first place, want to waste its precious time and resources (or that of its expensive lawyers) to engage in such a fruitless exercise for the benefit of a seller? Especially for an unknown or obscure seller?