You are warranting that the manufacturer used inferior cable in their own product. Would you also replace all internal wiring?
Not only wiring, but each and every component they use. With a few exceptions, manufacturers use mediocre components and wiring. Thats Economics 101
Wiring is difficult to change and wiring changes really shine at longer lengths than typical lengths of hookup wire. Internal speaker wire I always upgrade. I have, and will continue to upgrade all signal carrying cabling/wire in my amps were possible. That is a mod that I generally do last, and only if fairly easy/convenient. Not possible on PC boards of course.
An improvement in sound quality would have to be entirely subjective
In theory all sound is subjective right? However, after swapping out component for more than 20 years there is no if or buts, swapping out to higher quality components in key areas does 100% improve sound.
BTW The toaster and microwave was tongue in cheek and I stated their sound didn’t improve. The day I start listening to my toaster I need to be carted off to a home for the infirm.