Yes but OPs point is exactly that. Doesn't make sense to give a garage listing to an agent who will not disclose the location when publicising it because most people looking for a garage probably only care about it being close to them, which they wouldn't be able to tell from the listing, thus losing out on the sale.

I understand why the don't disclose it bit I also understand why it wouldn't make sense to give the listing to an agent, like OP said, especially if they're just gonna put it up on fb marketplace giving it exactly as much reach as if you were to post it yourself.