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.
Small screen, combined with poor/touch screen controls, and wanting to make money no matter what by pushing ads everywhere because no one wants to pay $10+ for a mobile software.
The only time I consider a mobile a game is when there is an ad-free option available.
I still miss my Xperia Play. It’s been over 10 years… Still my favorite phone.