I think it's a fallacy to say that just because Git allows a completely decentralized organizational structure, that not using one is somehow wrong. The beauty of git and any other DVCS is that it doesn't prescribe any specific organizational structure, so you're free to adopt any structure you like on it. And critically, you're free to change it when it makes sense to do so. I think the reality is that a centralized structure works best for most projects most of the time, but git has the flexibility to break out of that mold.

For example, maybe in one project most of the time everyone pushes and pulls from a centralized master and not to and from each other. But then two developers get together to try and solve a particularly troublesome bug. While they're doing this, they can push and pull directly from each other without worrying about master, and then once they're done, they can merge, clean up, etc., and then push the result to master. Git allows these kinds of pockets of decentralized development within an overall centralized workflow, and does so seamlessly.

Since Git allows any organizational structure, it's up to the people working on a project to choose what works best for them. That's a responsibility that they didn't have before DVCS, because only one structure was supported by the tools.