They usually are free to play with predatory monetization mechanics. That was especially back in 2016 when thanks to these games, the mobile gaming revenue outpaced PC and console gaming revenue.
I think it’s cultural differences. In the west, we abhor pay to win and predatory aspects. But in Korea, China and other countries in that region, players demand it.
So then it comes down to which market region you’re targeting. If you’re not a NA/EU mobile developer, how do you choose? 🤷♂️ Can’t keep everyone happy.