"Need"? Not really.
"Want"? Absolutely, apparently.
But it is their house, so their rules, and the issue of corruption in the world won't be solved overnight. The same if someone says "you can't smoke weed at my house", okay then... you know what to do about it - find another house, or even make one on your own.:-)
I only do it once a day even - the flossing part before bed is by far the most important iirc.