Ask HN: Why isn't there a leader in collaboration space?

Dropbox, box.net, google doc and google cloud connect, oneNote, etherPad, various IM client, Lotus Notes,etc

All the above companies complete in the collaboration space. Their service is to empower people or team that are scattered over several locations to communicate more effectively and work together. The companies above provide different variations of collaboration solution, share documents in the cloud, some have version controls, instant messaging, etc

It's safe to say the above companies are all very successful but why isn't there a leader(s) in the space? I've use all of them and somehow something is still missing in each of the solutions provided and I can't seem to pinpoint it.

HN, discuss what's the strength and short coming for each or all the above solution and what's your perfect collaboration tool should provide? Is there a leader in this space I did not identify?

Wil