It provides them with an environment where they can develop at their own pace, and socialize with other children who think alike, which might not happen with only regular classes, where being gifted can be a disadvantage. I believe the programs are usually not full-time, but an addition to normal school hours.
This, to me, seems very different from being a better path to success as it apparently is in the US, in some kind of segregated system where millions of children are enrolled, up to 15% in some states.
Most studies I've seen also show that over the long term, gifted education does not result in better life outcomes, and does not eliminate differences in background (like being poor vs rich).
