>>1232395>There's a damn good reason for that, anon.Vertical and horizontal integration of the supply chain, and not being bound by dumb unnecessary constraints to make your stuff interoperate with your competitors' stuff. Pic related, it's
>>1232352's motherboard. See how it implements standards that make sense (PCIe, PCIe power, ATX CPU power), but avoids having to waste money implementing the ATX connector, all the other voltages it requires, and all the associated wiring (this later led to the ATX12VO standard), and saves needing a dumb front panel board and of that wiring because the motherboard runs the whole length of the case and provides the front panel and back panel.
>but what if I want to replace the CPU?You can
>but what if I want to replace the motherboard The motherboard is the computer, so you'll need to get a case and a PSU. Cope.
>'cheaper' doesn't mean you're getting the best deal for your money.Definitionally it does. Don't be salty your big box costs more and the wires are all the wrong length.