I don’t think the different definitions make the debate “futile”: the real debate is about whether or not it is legally legitimate and economically desirable for banks to lend sums handed over to them by customers in exchange for contractsd offering so-called “demand deposits.” There are ways to settle this, that aren’t merely semantics. The trouble is that the 100-percenters think that by insisting on what the term bank “deposit” ought to mean (but in fact hasn’t ever actually meant), they also succeed in making a substantial argument on the real matter at hand.
Leland Yeager recently wrote a very good article concerning, not the futility of the debate, but that of the mode of argument just referred to. It is called “Bank Reserves: A Dispute over Words and Classifications.”