I suspect what you are referring to as surface scraping is actually the pattern used to retain oil on one of the mating surfaces of the slide ways. By the time that had worn way you'd be looking at a very badly worn machine. The pattern is added after the slideways have been trued up. Creating them makes no difference to the accuracy of the machine. You will most likely find that the mating surface is unscraped and may also be chromed for wear resistance.

However, it does sound as if it's a good example and despite the damage to the board, everything else looks very clean and tidy.