For example, designing a flex PCB with a 90 degree bend and a small inner radius like you might see on a mipi display or camera makes it extremely difficult to service, but has very little effect on initial assembly. If you design it for serviceability, you might do 2x 45 degree bends or a rounded pcb plus a stiffener above the mezzanine connector, reducing the chance it may tear or have broken joints.
I guess what I'm saying is just because it hasn't been designed to be serviced, doesn't mean it was designed to be unserviceable.