I understood what you meant, Maisy, but it just don't think it applies in the case of FC. Believing in FC doesn't shield a child from any harsh realities I can think of, just as experiencing him as a nice story/game that's imaginatively, but not literally, true, doesn't bring a child any closer to 'what's bad in the world.'
I think some posters are imagining small children being brought up in fun-free, Christmasless households where any mention of FC gets them a sharp rap on the knuckles, but in our house, at least, it's probably exactly the same as yours in the run-up to Christmas, apart from the fact that our son thinks of FC as a nice 'let's pretend'.
Vegan, my son thinks of FC pretty much exactly as he thinks of the Faraway Tree - involving, fascinating stuff he adores having read to him (particular favourites are the Land of Goodies and anything to do with the Saucepan Man!) and playing when we're walking in the woods ( might that hollow lead to the bottom of the Slippery-Slip?) BUT he has never thought MoonFace, Silky and co were real. They're stories. Just as FC is fir him.
Farewell, you might be surprised. I would say around a quarter of my friends with kids don't 'do' the FC is literally real approach - some of course because they come from places with different Christmas traditions - but I'm pretty sure that no one knows we don't among our acquaintances in the village we've lived in for a year. We don't go around proselytising!