The forum is a very strong believer of free speech and freedom in general. The ability to create alt accounts is necessary to allow free speech. If you limit what an alt account is able to do, you are in effect limiting free speech.
People often make alt accounts to just further their own, singular viewpoint, or to shill, spam, etc. I don't believe that manipulating the forum with alt accounts falls under the category of "free speech." Its dishonest, capitalizing on the goodwill of the community & shouldn't be tolerated.