Please excuse my severe "dumbness".
I wish others in my own community (though not of my own particular faith) A "Merry Christmas" because that particular day is a day of great joy for me.
I have no problem at all wishing others in my community (though not of my own particular faith) a Merry Christmas because I sincerely wish that everyone, on a day of great joy for me, also experience something on that day that will make them "Merry". The thing that makes them merry on December 25 does not, in my own view, have to havfe anything to do with the religious significances (to me) of that date.
It is merely a wish that I extend to someone else that they, too experience joy on a day that is most special to me.
I think it sad that you would consider such a wish to be "dumb".
I will tell you (in case you have not already guessed) that I am not Jewish. Nonetheless, I always appreciate it when my Jewish collegues or Jewish folk within my community wish me joy or happiness on one of the days special to them.
I do not consider them "dumb" for doing that.
Instead, I graciously thank them for their expressions of joy.
Am I missing something??
Suppose a Muslim wished you a "Happy Ramadan"?
I think it sad that you would consider such a wish to be "dumb".
It's dumb because why would I wish someone Chag Sameach on Shemini Atzeret when they 1)have no clue what it is, 2)if they did it would not mean anything to them as they do not celebrate it, and 3) If they are like many on FR would instead take the opportunity to either 'witness' to me or tell me about their lovely Replacement Theology?