It's likely the patch wiring was factory fresh, some of the component rework as well. Productions runs were relatively small (price premium vs. economies of scale) and rework was common practice. Folks rarely opened Macs, or any other computers, just to look at the insides back in the day. Few installed upgrades, RAM or Cards in the Portable era, much less so in the later PowerBook era and those that did so were old hand micro geeks who almost expected to see patchy repair jobs.

That's my take on it anyway. With current fab methods, high production runs and impractical repair methodology, chucking a completed board reject is the least expensive option. This was not always so.