Well I'd be inclined to agree because climbing for extended periods of time is more cardio than anything... short, steep climbs though, I'd say weight training would help. One thing that me and my teammate did that helped a lot on the track was find a short steep hill, ride it over geared (53x16 and then 53x15) and basically climb it from a standstill on the incline, focusing on being explosive and powerful in the movements to get up. We called this "weight training on a bike", which makes sense if you think about it.