Comment by lars

I think this practice tends to encourage merging code later rather than sooner, which has caused more problems in code I've worked on than anything else. With N developers, you may end up with N or more increasingly diverging branches. If feature A and feature B subtly breaks one another, neither developer A or B will catch this problem until both branches are merged into master, at which point both developers are probably convinced their code works, and may have moved on. If they had worked on the same branch, the problem would have been apparent from the moment the code was written.