How often do you hear people express that the phrase "Merry Christmas" is upsetting or offensive to them?

Maybe I’m beating a dead horse with this topic, lately, but I feel like I am constantly seeing arguments for “Merry Christmas.” My Facebook feed is full of statements, on a daily basis, about how people want to say it and want to hear it. There are billboards and homemade signs and banners whenever I’m out driving around declaring that “its okay!” to say Merry Christmas.

I can’t seem to recall a single time that I’ve ever heard anyone say that they didn’t like it, or that it was offensive. Not even in private conversations with my atheist or agnostic friends. Perhaps people say that they think it’s fine to say either, or, but never anything against that specific wording. I have also noticed that for the loads of status updates and signs going up in favor of saying “Merry Christmas,” I haven’t seen a single thing that suggests the opposite.

Am I living in a bubble? Is the only counter-argument simply saying “Happy Holidays,” or is there really a battle going on over what we should be saying and somehow I’m missing it?