Here's the hole in your logic: even if Netflix has no desire to operate a particular business anymore (despite presumed profitability), if the business was, in the general sense, desirable (i.e. because profitability), then it would be worthwhile to Netflix to simply sell the business to another entity. Surely, for a desirable business, Netflix should be able to find a buyer for $1 or higher. That would let Netflix liquidate the asset / business while keeping the business running.
Tech industry economics are besides the point. Suppose tech industry economics expects (for the sake of argument, insanely) an internal rate of return of 300% on every dollar spent, while the IRR of the disc business is some measly fraction of that. By liquidating the disc business, Netflix gets to take whatever proceeds from the liquidation - even if it's only $1 - and put it towards other internal usages that it expects that 300% IRR from.
A price like $1 is so small that, presumably, you would go to whoever the current salaried worker is responsible for managing the disc business, offer them ownership for $1, and the manager-worker would happily take the opportunity to become a manager-owner of the desirable business that employs him at a price that anyone could afford.
Of course, in the real world, there are various costs involved. So presumably, (a) the costs associated with liquidation are lower than the costs associated with spinning off the disc business, and (b) whatever the cost associated with spinning off the disc business, no buyer could be found for at least the sum of that cost plus $1; that such costs are indeed above what the salaried manager-worker of the current disc business could afford.
Maybe that's bullshit, maybe not, I don't understand enough about Netflix's disc business to know. But Hanlon's Razor is the better guide here. Either Netflix's board is going where the money is leading them to go, or they're leaving money on the table for malicious reasons, and the second doesn't make sense since it would expose them to shareholder lawsuits.