I agree with Bobby that this says to the buyer "you tell me what it is worth to you". But ...
An auction comes with an ending date.
A buy-it-now comes with an ending price.
A pie-in-the-sky buy-it-now with make-an-offer does not include a commitment to ever sell the item and, worse, comes with the opportunity for the seller to accumulate bids over a period of years and then, maybe, pick one ... or, maybe, not.
I don't see that there is much reason for the buyer to participate but, then, tossing a bid at the seller does not take a whole lot of effort, either.
If this particular seller is paying rent (monthly fees, listing fees), then there is no harm done to the auction site ... that the listings are cluttered with stuff that does not move is offset by the revenue stream from the overhead fees.
Not the most exciting corner of
ebay for either the buyers or the sellers, but most days, most sellers at most flea markets take most of their goods home.
Cheers,
/s/ ikeyPikey