@Blickers,
Those metal things get stuck in a kitchen drawer of other metal things. They are a pain to fish out, they need to be filled and they need to be washed aftwards.
The humble tea bag, on the other hand, sits patiently in a neat box on a pantry shelf with its brothers waiting for me to put it into a cup of hot water. It is quick, easy, clean and it gives me a cup of tea that makes me happy.
(BTW, googling for an image of "teabag" leads to some interesting results)