I think it's probably a combination of sharing of knowledge and research, and presenting a more unified face to the outside public. As you'd expect in any sort of unorganized hobby, there will always be large numbers of small groups that have different ideas of how to do things, don't always communicate, and there can be very different standards for things like competitions, rankings, etc. Having an umbrella organization can help smooth all of these things out, and provides an opportunity to get it all on the right track before everyone gets too jaded separately.
I suspect they've considered all of these things when entering into discussions about what to do.
