[twentysixtwo]

My take:

1) Price discrimination is a well understood means of maximizing profit over a set of consumers with varying utility levels.

2) Rebates are a form of price discrimination.

3) Sales and discounts are another form of price discrimination.

4) Companies who knowingly don't close loopholes allowing discount and rebate stacking are allowing an additional level of price discrimination.

5) Discount stacking is understood well enough that companies who (unknowingly) do not close loopholes have made a conscious decision at a separate level that the downside and cost outweighs the benefit (i.e. marginal revenue greater than marginal cost.)

6) Network externalities mean that Sprint's marginal cost of providing me service is really miniscule. After rebate I will have paid $99 for my TP. At $30 a month they will certainly recover more than the cost of the device over the course of my contract.

In a nutshell, their yield management has to treat people like groups and not individuals and overall, even though some individuals may benefit more (resulting in smaller profits to Sprint) their strategy overall theoretically gives Sprint larger profits.