You can write to the same IPNS entry with multiple different computers, but i'm not sure that would be the desired way of updating this. One way i would imagine it could be done is using crdts in combination with some global immutable log (not necessarily a blockchain). Then there needs to be some sort of concept of identity to help avoid spam and trolls, I really like the idea of a web of trust, and that could very likely work here. I'd love to see more widespread applications of CRDTs