It have a very specific use case, and will keep giving a strong visibility to the old, unmaintained site, for people that had old links to it. A more comprehen

It have a very specific use case, and will keep giving a strong visibility to the old, unmaintained site, for people that had old links to it. A more comprehensive 404 page (that says that what what you were looking for is not there, and links to the current and the old site), or redirects for the most accessed URLs of the old site in the new one are better approachs in my opinion.