What I don't get about this argument is, with distributed version control, in a sense everyone "paints their part without even looking at what their partners are doing" even if you don't branch. Unless everyone regularly pulls from the repo, they're only going to see what's in their checked-out copy.
If you want to mandate that they regularly pull in order to stay up to date with others' changes, you can just mandate that they regularly merge master (or develop or what have you) into their topic branches.
I don't see how organizing or not organizing your own development into topic branches affects how integration with the rest of the codebase is handled. And as someone else pointed out, if every developer has their own fork of the code (the GitHub model), then that adds a further wrinkle that even this crazy "no branches" position doesn't solve.
I feel like this is trying to solve the wrong problem, by thinking that branching is the problem.
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