You are changing your argument as you go. But nevertheless, I say yes. Dell should eat $10M if they had sold enough to make that number (note, that number is seriously unrealistic because the rebates are limited to one per household, even with the fatwallet type coverage it is unlikely that 100,000 rebateable orders were placed during that time period).

We are all too lenient on big companies doing poor implementations of website ordering systems. It is not that hard to put a sell rate threshold on their inventory such that if the system starts to see an item sell at, say, 300% of its normal sell rate that a human being be notified who immediately investigates the situation, applies some of those human thought processes that we can't seem to teach a machine yet, and decides to temporarily suspend future sales of the item in question until the error is corrected.

Instead most companies just let the error go on unchecked for days and then half the time choose an unprofessional method to handle the problem, like "disappearing" the order without any trace or explanation, or putting the order into a permanent state of "waiting to be shipped" or (as HP did recently) calling up people who received the orders and telling them that they could either return the product or pay an additional charge (which is completely illegal). Some companies are at least gracious enough to handle the order cancellation gracefully with an email acknowledging their error, apologizing and sometimes offering a discount of some sort on a future purchase (note that a meaningless discount is worse than no discount).

But, nevertheless, if they had designed their website software correctly in the first place only a couple of hundred orders would slip through, if not less, and with those kind of numbers they get the PR of actually honoring their mistakes without the negative of losing any "real" money. One result of such good PR is that it will encourage people (albiet bargain-hunter types, but even they will make impulse buys) to spend more time exploring the website looking for deals. The more people who browse, the more likely someone is going to make an impulse, or otherwise profitable for the seller, buy. Everybody wins.