Leftists cannot stand patriotism! They already have the inconvenience of having to scurry from their seats in order to miss the National Anthem. Throwing in "God Bless America" just makes it more difficult in their effort to shield themselves from seeing the majority of their fellow Americans bellow proudly for their love of country.
There will be no borders in Utopia, thus no need for patriotism.
We'll love them anyway. Let them enjoy the game. Let them wash down their vegan dogs with a nice beer. That's America!