"Thanksgiving" implies that you are thankful TO someone FOR something. We do not want anyone thinking about Who we are thankful TO, now, do we?
/S
BTW, "Holiday" is just a contraction for the term, "Holy Day", i.e. "set apart for a sacred purpose". Sneaky how the truth seems to insist on being heard, even if never acknowledged.
I’m seeing many of our holidays challenged and subverted
Christmas
Thanksgiving
Veterans Day
Columbus Day
Fourth of July
But we’ve got new things like the corporate recognition of the Communist holiday “International Woman’s Day”
‘our traditions and history must change...’ (paraphrased from memory) - 1st Lady Michelle Obama