This sense of "bootless" has nothing to do with footwear. The "boot" in this case is an obsolete noun that meant "use" or "avail." That "boot" descended from Old English "bōt" and is ultimately related to our modern word better, whose remote Germanic ancestor meant literally "of more use." Of course, English does also see the occasional use of "bootless" to mean simply "lacking boots," as Anne Brontë used the word in Agnes Grey (1847): "And what would their parents think of me, if they saw or heard the children rioting, hatless, bonnetless, gloveless, and bootless, in the deep soft snow?"
Examples of bootless in a Sentence
a bootless effort to get tickets to the sold-out game