Even if you filter out the merge commits, then you're hiding some of the changes made when you look at the history of the branch. The other problem is that if you run git blame on a file and the line is referenced by one of those merge commits, then the commit message is next to useless. Those looking at the history want to know why that line is there (changed from a previous version or added). A commit message that explains the reason and allows you to see that line in a context of a logical change makes it much easier to determine whether the change you're planning to make will introduce a regression or lead to some other issue. A merge commit message with a mixture of changes that may pertain to any number of commits in the branch doesn't help and makes it harder to figure out what the change was.