Many items such as Decoys or vintage carpets will not have a Brand or Maker and likely we will never find out who made them.  With other items where an item is without its packaging, the packaging is there but does not provide the information or the language is in non-Latin characters (say Chinese or Japanese) but there is a reasonable expectation that somebody else will know the Maker use Unknown Maker as the Brand Subject.  Unknown Maker is not for any other type of Subject than the Brand.

Here are some good examples  -

Do you know the Maker for either?  Then you can add it!