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?
But intentions are not binding contractual conditions. Nor need they lead up to binding contractual conditions. Moreover a letter expressing intent, in its form, does not adequately suggest what the appropriate response should be. Whereas a Request for Quotation / RFQ quite literally is a Request. For a Price Quotation. Hence the document's name, it meaning is expressed by it's name. Hence an appropriate response, for a vendor or supplier, is issuing a a price quote.