video game arcades were skill-based gameplay, if you were good at gyruss you could play a LONG time on your quarter; yes, it was expensive while you were learning, but that promoted skill acquisition, the better pattern recognition, memory and hand-eye coordination you developed, the more you could play with the same amount of money.

IAP and coin-based gameplay is not skill based, it's addiction based, which is NOT something you should encourage: the reward loop is completely different, fear-of-missing-out and scarcity-based gameplay do not create any positive effects, save maybe training your child to be a future patron of casinos and similar establishments