In reply to shark:
Reading the study and the diet they show as 'typical' for a 70kg athlete, I suspect they have (typically) studied the requirements for endurance athletes, who tend to train way more than the average climber and also eat loads.
A climber who is trying to keep their weight low I suppose may struggle to get their protein requirements. Although it's worth remembering of course that protein isn't just found in the obvious things like meat and milk, but also crops up in bread etc.
Personally I did find that this statement rang true:
"Occasionally, an athlete may require a supplement when a practical way to consume sufficient food cannot be found. Many protein supplements are very expensive due primarily to the amount of marketing that accompanies products and the processing required to extract the protein from cow’s milk. They tend to provide very large amounts of protein and little other nutrients. There is no need for the amount of protein provided by many supplements and there is certainly no justification for the extra cost."
As with all things it depends on your individual diet and requirements. I'm wary of the amount of sugar in these supplements, tend to find they don't taste nice but rather chemically, and generally think that high quality dietary protein like tuna or eggs (Niçoise salad anyone?) trumps a supplement.