If I am opposed to cairns, I must be opposed to trails? I won’t bother to comment on that.
I have made plenty of route-finding mistakes in my time, costing me time, effort and aggravation, and in some cases being risky as well. I can’t say cairns have had much to do with them, one way or another. In the great majority of cases, there were no cairns. When I do see a cairn, I notice it, but I don’t particularly trust it. I regard them as more due to individuals who like to leave their mark on the wilderness, than as a navigation aid that can be trusted.
And, once again, we now have GPS. Whatever the arguments once were for cairns, GPS is far better, and easily available by installing an app and map.
I am curious, where were the cairns on the East San Bernardine Peak trail? Trails in the SGW are generally very clear, and the only error you can make is taking a wrong turn, something that can make a sign useful, but not a cairn. There are use trail spurs to summits, but Hundred Peaks Section route-descriptions and GPS are aids that can be trusted and leave no mark.