Regular tea drinkers do. Otherwise, they aren’t useful.

Light tea drinkers don’t have a use for them because for single cups now and then, you’re better off nuking the water to temp.

Hell, I have a cup almost every day, and that’s still not worth having another thing on the counter for.

The U.S. is more into coffee than tea overall. But I know plenty of people that drink tea often enough to merit having one and using it.