Suppose there is a huge rock feature that's not going anywhere. Consider the following rigging options:
(1) Tie around the whole thing.
(2) Put two bolts in and attach the rope to those.
Few would dispute that claim that correctly placing two bolts of modern construction in good, solid rock and rigging off both of them with a load sharing anchor that minimizes extension is a very acceptable way to rig. Option 2 fits this description and is redundant. Option 1 is not even redundant. Which is safer?
Suppose you are considering backing up your huge rock feature tie-off with another huge rock feature tie-off. Would you really put two more bolts in, if you were rigging with bolts? Would you even use them if they were already there?
I would rather hang my life off a single bomber anchor point--that is, one with no substantial chance of failing (e.g. a large living tree that has survived previous caver rigging, rescue rigging, and hurricanes; a huge boulder; a large, solid rock feature that's been there a real long time), than *any* number of anchor points that *should* be good enough...but maybe, just maybe, aren't (e.g. bolts, rock and ice protection; boulders that are probably attached and probably heavy enough, probably; small trees). When rigging off the latter kind, I always have at least two--if rock or ice protection, at least three. But I prefer one of the former kind if available.
The doctrine of looking for a single, bomber anchor point first is by no means accepted everywhere, and in many situations there is no such anchor point, but to say that using one is "somewhere approaching Darwinism" is to ignore a long and rich history of caving in the United States in which people have done this and experienced no problems. Not only has this practice not been eliminated over time, but it is taught to and used by rescuers.
Theoretically additional security is achieved by backing up a bomber anchor point that is guaranteed to be stronger than the rope and individually good for catching falling two-person rescue loads. Rescuers don't do that because time (and to a lesser extent, gear) is a resource. (Granted, there is a separate belay, but my understanding is that it is acceptable to have the belay use a separately rigged anchor on the same bomber anchor point as is used by the haul line.) Preservation of time and gear may not be essential in sport caving, but I would ask whether or not it is really worthwhile to exceed standards for rescue rigging in one's sport rigging.
Furthermore, even in sport caving, I would say that *simplicity* is a resource. You arrive at the drop and it is not even rigged--the most simple configuration. But that is unsatisfactory, because this simple state does not permit safe negotiation of the drop. So then you rig something, and use up some simplicity. The more you rig, the more simplicity you use up. The more simplicity remains, the easier it is to look at the anchor or anchor system and know that it is correct and what can and cannot safely be done with it. I think an anchor that minimizes risk of catastrophic failure while preserving as much simplicity as possible is practically the safest option.
(Also, I would dispute the claim that how you rig your caves is genetic.
Furthermore, I suspect that the extreme, life-threatening stupidity of some is actually essential to the survival of the species and thus will never be eliminated evolutionarily. But I'm not an evolutionary biologist, and that's
.)