That's not necessarily the case though. I've got a friend who has a really horrible benchtop saw with a fence that simply cannot lock parallel to the blade. The second you lock the fence, the back of the blade shifts about 1/8" The arbor has considerable runout. We have tried many times to fix the fence and this is the smallest shift we've been able to get. You cannot get a better fence from the manufacturer, they don't make one.
That's why he's been over using my shop and why, this weekend if it's not raining, we're off to buy him a brand new saw. The old one simply cannot be fixed and wouldn't even make a good doorstop.