[robots0only]

Here you can see another much simpler robot folding clothes for far longer: https://www.youtube.com/watch?v=gdeBIR0jVvU (there are more videos from other companies as well)

To answer your question -- folding clothes is easy, because clothes easily deform, do not break, fall smoothly when you drop them and most importantly are easily resettable task. Just through the well folded cloth up and voila start again.

[imtringued]

Actually, folding clothes is a challenging dexterity task. However, it's a trivial mechanical engineering task, which is why it is so popular with underpowered robot arms.

[robots0only]

How are you defining dextrous? I think it can be somewhat challenging but not dextrous -- the robot doesn't need to be very precise (few cms here and there do not matter), there are no forces involved, motions are all pick-place. Dextrous tasks would be things like shoe-lace tying, origami folding etc.