When we expect to make a decision, we are in a massively different head space.

When we are passively watching something, our brains can wander with no real downside.

But when we expect to have to make a decision (e.g. in a game, or when executing in our job), we are constantly absorbing all relevant information, balancing across a lot of possibilities, developing an intuitive predictive model, and being ready to have a decision if someone said "OK, go time, make your decision RIGHT NOW".

The two situations look somewhat similar externally but are radically different inside the mind.

The latter has orders of magnitude higher rate of knowhow acquisition: much faster learning rate.

This is why simulations, games, and play are so good for learning.