Not the guy you responded to but I use and am a big fan of the same thing.
Doesn't that require a separate filter for each cup?
Yeah, but they're cheap and very convenient for preparation and clean-up.
And a tea kettle or some other 3rd party heating solution?
Yes, but once you know how long it takes for e.g. a microwave to safely get a certain amount of water to the optimal temperature for a single serving it takes a very short amount of time. I know my microwave at home takes 2 min to get 12 oz of cold water to the perfect brewing temp.
Also I know that the particular vessel I use to microwave water has nucleation points which allows the water to safely come to a roiling boil which keeps the water from superheating and exploding.