Didn't say I was lost - just looking for confirmation that the path I expected to find was actually here; or that the route across the boulder field I was crossing was the 'right' one. I stress I'm talking reassurance in adverse conditions here, not reliability. I can remember a couple of occasions when all the signals were confusing, including the compass readings I was getting in the Bowfell area in zero effective visibility. And there was a close-to-panic half hour in a bitterly cold total white-out (fog AND snow) on the east side of the Fairfield horse shoe. As it got dark, I and my companion were very tired after a long day, and could make little sense of anything. In those conditions, when your brain tells you to go in one direction and your compass tells you something different, a simple thing like a cairn - and finding the next one - can focus your mind.
I suppose if you've never experienced these conditions, or if you're a fine weather outdoors type who ONLY follows obvious paths (where cairns just get in the way), then yes, you can be dismissive of the utility of cairns, and insulting to those who think that they may have their place. Of course I know the difference between a cairn and a rock-mole hill, and yes I do think there are too many cairns in unnecessary places. All I said was, there have been occasions when they were useful to me.