I’m not a cool kid so I didn’t know about it 🙂 I know some cool kids, though, so I’ve seen similar things for other hobbies.
I wargame a limited number of periods and scales, and the details are too vague for me – “a mixture of sci-fi, fantasy or historic models and accessories”. I assume the benefit is that what you get would cost significantly more if you bought them normally.
I quite like the idea of getting random surprises in the post, but not enough to real money on it. These things always seem to cost upwards of £20/month, though, which is way too much for me to spend on the possibility of maybe getting something I’d like.