Let's imagine for a second that the bug-fix you make isn't perfect. Maybe you ought to have refactored something a bit more instead. Maybe you made the bugfix a couple days after making the main feature commit, and you'd forgotten some detail. At any rate, half a year later someone has to sit down and figure out why the code is behaving weirdly sometimes. If you've got an accurate history of how the code was written, they'll have an indication that the code from the bugfix was added post-hoc, and might be inclined to investigate here. They'll understand that all these lines of code were not written at once, so the ones in the bugfix are more likely not to be fully cohesive with the rest of them.

Sure, in the happy case where your code is perfect, all those extra commits are just 'noise'. But when debugging, there can be value in the forensic information about the evolution of the code. Which also documents the evolution of the understanding of the person that wrote it. It can help answer questions like "why is _this_ here?" or "what were they thinking?!?" I've fixed bugs that would have taken much longer to narrow down if I hadn't had clues like that.