Not true. The arm/rail is not perfectly rigid, the bearings are not perfectly true, and the latches have hysterisis. Even if you could set it up perfectly (you can't - there aren't the adjustments), it wouldn't hold them for a cut. Errors add up.
That may be true and for framing, it probably is. They're not so good for finish work, though. Note that I have their 10" SMCS and it's well worth the $100 I paid for it ten years ago. It's no match for my Bosch, though (and the Bosch is far from perfect). Yes, I still use both.