What is really funny to me is there are several conditions that are easily to poke holes at.
First condition: was it built as a whole bass by Fender and is that how it left the factory? I understand that one. But what if the bass was sold to stratosphere parts, who in turn broke it down into two separate items: a loaded body and a loaded neck. Now you as a customer buy both of these parts individualing and either know or do not know that they originally belonged together.
The parts arrive at your house and you install the neck with the four bolts,
Parts bass or Fender bass? Note that it is exactly the same bass in the same condition as if the customer had bought it directly from Fender and had taken the neck off to adjust the truss rod just once.
Second conditiion: Fender did the manual work wiring the pickups and pots together. In the case of buying all the correct parts directly from Fender the one obvious thing that won't be duplicated exactly is the wiring together of the pickups, pots, etc. Now consider instead that you bought the bass as a whole from Fender some time ago and have a few scratchy pots that can't be fixed and must be replaced. You order the correct replacement pots from Fender and install them. You may or may not choose to use new wire perhaps based on the age, condition, or skill with which the existing wiring was installed. You have now repaired the bass. At some point you may have removed and replaced the tuners, neckplate, bridge for cleaning. But as it stands, now the bass is in exactly the same condition as if you had bought it a separate parts because now it is your own hands that have assembled everything as it is, even though the bass was shipped whole from the factory.
Third case: every single part on a bass is made by and sold by Fender. You use the parts as Fender intends you to. There is no other manufacturer involved excpet any oem who supplies Fender with parts that they both use and resell. It is completely irrational to say that bass is not a Fender bass. Fender says that it is a Fender bass. Every part you have bought is distinctly branded Fender by Fender. I can buy a "Tuff Shed" at home depot as a whole solution or as individual parts they deliver to my yard for me to assemble. If I choose the parts route and assemble it myself it is no less a Tuff Shed than if they deliver it preassembled, or if they choose to bring parts and assemble it onsite.
Fourth case: people restore old Fender basses by tracking down and matching up period correct parts. These basses did not leave the factory together. But if you find and assemble all the right and relevant parts then you have 1962 Jazz Bass, or whatever you were building, except that it is no different from building a new parts bass today when you set aside nostalgia. People don't frown on calling these basses Fender Jazz basses.
