The only problem, is that spawn 'points' are not points, but they are spawn areas, And the way, npcs move around objects currently, it may have its bugs...as currently if you attack and run, they will 'try' to go around things, but generally I have seen they dont go up or down slopes/ledges, and i have also noticed, the will run into objects.
Anyway, the way I would see it, if they moved towards the spawn area, they would end up being stacked, in their spawn area, unless they were programmed, to go back to the specific spot they spawned, the very last time they spawned...