title: Why is --first-parent not the default for git show?
body: <p>I'm sure this question will be closed as opinion-based but there's nowhere else so ask it so here goes...</p>
  
  <p>I'm trying to view the history of my branch which includes merge commits (specifically what changed) and I found a very useful post here <a href="https://stackoverflow.com/questions/40986518/git-show-of-a-merge-commit">git show of a merge commit</a> that tells me to use <code>git show --first-parent</code></p>
  
  <p>What's still confusing me is why <code>--first-parent</code> isn't the default for <code>git show</code>, or even why any other behavior is useful at all. If I'm looking in my history on a specific branch at a specific commit, the only thing I ever want to know is the difference between that version of the branch and the previous one.</p>
  
  <p>Of course it could be that git commands are written for the convenience of the authors who don't give a shit what their end users actually want, but I suspect that there is a proper reason. Could someone explain why, with a better knowledge of git, I might not want to use <code>--first-parent</code> all the time.</p>