Because when debugging with said history a week or a month down the line, or when someone else is debugging with said history, their human comprehension is essential for understanding why a certain event in the history is causing problems and what that event was intended to do.

That seems connected to the initial claim in only the most tenuous way.

In the Linux kernel mailing lists, which are the submit-by-email culture I'm most familiar with and with the best documentation of norms, the main criterion for individual patches is that they be comprehensible to a reviewer. Reviewers and bugfixers face similar reading comprehension constraints.

But why should any of that apply to my version control system? I'm not developing the Linux kernel on a mailing list.

It shouldn't for your personal stuff.

But it absolutely should when you work in a team. I'll personally scold you if you waste my time with merging a 20 commit PR of which 10 commmits are "fix stuff" or "fix typo" or "oops forgot variable" etc. It won't pass code review.

You are free to disagree. I am only telling you how it is in many companies.

But why? What problem are you actually solving with this?

1. Waste of code reviewers' time

2. Waste of later coders' time when running git blame on a line when trying to figure out the purpose of code

3. Waste of later debuggers' time when they need to decide whether this error is the thing they're looking for, an unrelated error to bisect skip, or an unrelated error in possibly-related code that they need to manually fix and then re-test.

As the other sibling poster says, it's about not wasting other people's time. Make the messages/descriptions ruthlessly short and to the point and your colleagues will like you.