A lot of strength training for other sports is quite generic though. Doing squats trains big muscle groups and rugby players do also spent considerable periods of time on eg scrum machines to train the specific strength they need as well.
Its plausible that in climbing because holds are so variable, the specificity of training one grip type might mean that it doesn't necessarily translate well to outside/ any other climbing where that grip type is not used. Perhaps its more specific than other sports.
Obviously its not a holy grail of training to fingerboard like this though.
I would say its quite common for sports to say "we're not like other sports, we are different!" but in reality the principles of S&C come from biology. I'm not saying that Alison Vest is or isn't doing the best thing, I think it's fair to say we don't have sufficient science on finger strength training for real knowledge
But what I would say is that if you are able to, with consistent form, that does not provoke injury and does target the appropriate area, increase load through an adjustment of the finger position, then that could have a positive impact.
I know that there's an idea that just training on a 20mm edge just teaches you how to get stronger on a 20mm edge. I'd say that's not true. Fingerboard hangs make your fingers stronger across a lot of hold types.
Anyway clearly hanging that way is not giving her issues
Wellsy, I see what you're saying about basic training gains giving you a foundation for more more sport specifc gains, but there are many, many examples, papers, studies etc. that all point to the same thing - finger strength gains on a 20mm edge *without lots of movement practice and learning how to apply that to rock, results in poor gains in terms of grades and ability*