Because we trust them more than you. Not that we don't trust you, but when a link come from an uploader, we know for sure that the files have been tested against most threats. When it come from someone else, we can just assume that they've been. And this make a big difference.
By the way, the need to provide mirror links is for the uploaders. No one effectively expect the game author, or the guy who answered to a request, to provide more than one valid link.
You missed or disregarded the main key point of the question I posed:
What about when they're reuploaded to the same host? That seems like nonsense.
In this case I earlier shared a game update and one of the links I used was GoFile.
I find out that who whomever edits the main post of the game subsequently
reuploaded it to GoFile.
"We trust them more" Pfft. The (paid for) file I shared came from his personal file server and was shared in an unopened, unedited form in the original archive it was supplied in.
I'm not saying that my links are any better than the next guy. But if you're not going to use the links provided, why even have a requirement for them?
Not once did I mention the game author. Why even bring that point up?