Avoiding the merge trap

Topic branches are useful when you're working on multiple independent topics concurrently. It doesn't matter how many commits on the branches there are, it can be a single commit or dozens of them: while your patchset is being reviewed for inclusion you can switch to other topic branches to work on the other subjects.

To me, part of the value of a merge commit is that it records when and by whom the code was merged into the target branch.