Why does only Christmas get a Merry? Everything else gets a Happy. Why does Christmas have a monopoly on the Merry?
Happy Thanksgiving, Happy Easter, Happy Hannukah, Happy Valentine's Day, Happy Groundhog Day...
Just because Mary factored into Christmas doesn't mean it should have a lock on Merry. They are homonyms, not synonyms.
![Stick out tongue :p :p](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)