Earlier quoted context omitted.
For low-end machines these bundling deals likely form a sizeable chunk of the profit margin. (I've heard eyebrow-raising numbers for e.g. the default browser spot.)
Yep. The other chunk results from the OEM's refusal to stick to any long term consistency in the components they spec in consumer lines of devices. In business lines, you will likely get a 6-12 month guarantee with a 6-24mo forecast showing exactly what is shipping with what (CPUs, GPUs, screens, hard drives, etc). With consumer lines, they change components & suppliers any time, for any reason.
I always love when the same model (down to the part number) comes with a different configuration and board inside the case.