I don't think so, because I think it's less-reasonable to expect the OP to maintain thousands of price listings than it is to maintain one.
Of course it's less reasonable, but that doesn't mean it didn't happen. People are lazy. If OP wasn't using the mass price tool and was manually entering the prices for his cards than I have 0 sympathy for him. In that case it's 100% his fault for not updating earlier or temporarily putting his account on vacation mode.
On mass pricing: You can't just mass price your entire collection and expect to be covered if one of the cards spikes in value. You listed the card at that price so you have to be ok with that price. If you're not on top of updating the price that's your fault, not Deckbox's. I will concede that the mass pricing tool isn't perfect, but for listing all of your bulk it's super convenient and I believe that's what the original intention for the tool was.