A common thing that JWs point to as proof of God's blessing is the supposed cooperation between people of many different backgrounds. However, I think there should be a distinction drawn between collaborations that are performed through true tolerance and open-mindedness towards another's point of view, and collaborations that are the result of a high level of conformity by its participants.
The former sort can be seen, for example, in the UN, which while not perfect, I believe does try its best to foster true cooperation between people of all nations. The latter of sort of cooperation, however, is more akin to the type found in communist dictatorships or countries controlled predominantly by a single religion which doesn't care to protect the rights of those in the religious minority. I hope most people would agree that the former type of cooperation is morally better.
The type of cooperation shown amongst JWs is clearly of the second type because failure to conform to their rigid rulesets or social conventions is rarely met with anything but disdain. Conformity based cooperation doesn't scale up quickly because that cooperation doesn't extend beyond the group, so cooperation amongst different sets of conformists is rare, to say the least. In fact, I think it can be more difficult for a group of JWs to work collaboratively with non-JWs.