I agree with you, but to be fair, the sensor I am currently wearing (which is being replaced) has been just wonky - both high and low, although mainly significantly high. My "working range" is pretty low, so variances of 1.5, say, are significant in terms of accuracy, if not necessarily in terms of how I react to the reading.
I think it's fair to expect that this device will show variances, but such variances should surely be similar those allowable via a meter.
I absolutely love the Libre, but it can be frustrating when the wiggly line gets a lot wigglier than it should!