HIIT is not meant to train you for long distance and I never ever heard anyone to claim so. How to skate 10kms is competitive athlete program and had literally nothing to do with goals of normal sedentary person exercising.

For a lot of people, actual ability to run up stars higher or be active for 20 mins with kids is what they want and need.

And it is fun. It feels good. You see improvements in own ability to do day to day things. It takes a while till those wear off and you start to stagnate.