Which is fine for single item repairs or upgrades where the person doing the work is tech savvy and all parties are will to accept the loss of a functional devi

Which is fine for single item repairs or upgrades where the person doing the work is tech savvy and all parties are will to accept the loss of a functional device in case something goes awry. (Which, admittedly, is rare, but you have to take the liability on yourself every time). Something like that is entirely non-feasible for mass manufacturing of parts with any guarantee of quality though.