If you leave broken commits in the history, you'll make it very hard to use tools like "git bisect". You can "skip" broken commits, but that should be an occasional exception. It doesn't matter if that was on a personal branch either, because once you merge it's all part of the same graph of commits.

I have no problem with broken commits locally, but I don't want to see those in a public tree. Merge or rebase with squashing, please.