Are you an advocate of an OEM purposely keeping consumers from using another companies product though?You folks know me as a strong advocate for OEM chargers and OEM cables, but not for the reason of profitability (duh...). I happen to know that for a fact most third-party charger adapters use terribly inferior components, much simpler voltage step-down components, low-level AC to DC converters and crude filtering, and ultimately produce very dirty DC voltages. Dirty power being pumped into these EXTREMELY sensitive devices with circuitry in the processors, for instance that have "wires" (printed conductive traces), which are (as in the case of the processor in the S4), 28nm or smaller (28 nanometers or 28 billionths of a meter - .000028 millimeters - 28 one-hundred-thousandths of a millimeter), causes these extremely small components to suffer stresses (expansion and contraction) due to the power fluctuations. It increases power consumption and causes heat as a byproduct as well.
Take duplicate copies of the same circuit and run one with clean power, the other with dirty power. The one with the clean power will run faster and with less heat generated, as well as will remain in operable condition far longer than the one supplied with dirty power, all other things being equal. The MTBF (Mean Time Between Failures), drops precipitously and directly proportional to the purity of the power source signal. CPUs will run faster and cooler, they will last longer, and the overall user experience will therefore be a better one.
Furthermore, if there's one soapbox I get on often, it's proper care and charging of Lithium Ion Polymer Pouch type batteries (the types used in most phones of today). These batteries are very picky - to use a common descriptor, with respect to how they are charged (at what percentage of capacity or discharge charging is started), at what rate the are charged (mAh, i.e. 750mAh, 1.1mAh, or 2.1mAh, etc.), how much they are charged (percentage of rated capacity, or maximum voltage levels), and how much they are discharged (minimum voltage level). They are very volatile chemistry and if not charged in the ranges as specified by the manufacturer of the phone when they specify the chemistry to meet certain needs, the results can be anything from poor performance, to shorter total lifespan, to complete failure to respond to a charger, to self-destruction and explosion/extremely high temperature fire.
I've opened dozens of charger modules, those from the big named cellular phone manufacturers, those from the big named phone accessory manufacturers, and those of the cheapo Chinese knock-off companies, the $5 chargers. To compare them is similar to comparing a BMW 5 series to a go-cart. Both will get you there (eventually), both burn fossil fuels, and both have a seat and 4 wheels, a steering wheel and a motor. The quality and perhaps even more importantly safety of the trip and likelihood you arrive in one piece in one versus the other are unfortunately incomparable. The number of components, quality of those components and engineering which comprise two are beyond compare.
I will post some photos when I get a chance, but safe to say the OEM chargers have not just some, but LOTS of components, usually several MSIC (Medium-Scale Integrated Circuit) chips, quality filtering components and are engineered to provide the cleanest, smoothest possible power. The cheapo's have just a very few components and very little filtering of any kind. To give you another real-world comparison...think of the OEM charger as a brand-new paved Asphalt road, versus one that is 15-20 years old, full of potholes, patches, repairs to the piping underneath, etc. Again, both will get you there, but one is a much more comfortable ride and will not produce wear and tear on the car, whereas the other may cause you a blow-out or at least to need an alignment, both your back's and the car's.