Because when debugging, you typically don't care about the details of wip, some more stuff, Merge remote-tracking branch 'origin/master', almost working, Merge remote-tracking branch 'origin/master', fix some tests etc. and would rather follow logical steps being taken in order with descriptive messages such as component: refactor xyz in preparation for feature, component: add do_foo(), component: implement feature using do_foo() etc.

You can have both. I'll get to that later. But first, let me explain why edited history is useful.

Unedited histories are very chaotic and often contains errors, commits with partial features, abandoned code, reverted code, out-of-sequence code, etc. These are useful in preserving the actual progress of your own thought. But such histories are a nightmare to review. Commits should be complete (a single commit contains a full feature) and in proper order. If you're a reviewer, you also wouldn't want to waste time reviewing someone else's mistakes, experiments, reverted code, etc. Self-complete commits also have another advantage - users can choose to omit an entire feature by omitting a commit.

Now the part about having both - the unedited and carefully crafted history. Rebasing doesn't erase the original branch. You can preserve it by creating a new branch. Or, you can recover it from reflog. I use it to preserve the original development history. Then I submit the edited/crafted history/branch upstream.