As long as the blend is uploaded by its author and only contains content created by the author, including images, reference drawings, etc... I think it would be important to have such a permanent location for files. Mainly for the purpose of preventing dead links to what would otherwise be helpful content.
In my opinion, if a blend or graphic is created, and intended, for the sole purpose of assisting others, it should be copyright to the author and placed in the public domain by the author in order to reach the most users, not only on stack exchange, but throughout the entire WWW. This would still require the person using the content to acknowledge the copyright, but also allow the person using the content to not be required to display a credit of some sort, like a majority of open source licensing options require.
If I offer help to someone and it is useful to them, and they think they can make money from that help I offered, more power to them. I wouldn't require them to credit me with anything. Just them using the help is credit enough for me. I know many people don't share this same opinion but to me it just makes the most sense.
I cant imagine anyone having to keep track of everyone that offered assistance with some issue or educational material. You would have to credit all your school teachers, the authors and publishers of school books, pen and pencil manufacturers, paper manufactures, PC manufacturers, etc... etc... etc... that all assisted in giving us the skills required to do what we do.
So if it was posted to help others, the author most likely would appreciate the fact that others are still using and sharing it. If the author included an email or postal address in the content, send a mail to it explaining where and why you are keeping it available. Even if they don't respond they will at least know who to contact if an issue arises or if they want you to take it down or update it at a later date.