I'm in the game industry. This is entirely person observation I have not studied this topic so can't source anything

The people I saw going to early mobile market were a lot of handheld console and flash game devs and companies. They were adapting the closest existing game designs and brought with them a "small game small cost" philosophy. It also wasn't really known yet how impulsive people are on phones. So it was an unproven market with smaller teams and people making yester era design choices. There also used to be a few bigger games with bigger price tags but people didn't buy into those because anyone willing to spend that on a game at the time would have had a console or PC and could buy a better experience there for the same price.

The only mobile game experience I have was back in like 2012, smart phones were really taking off, and the market for mobile games was proven. The company I worked for we built a release ready game but it never got released. We couldn't sell it to investors because the monetization was never aggressive enough for them (the investor money at that point was less about making the game and more to fund marketing and stabilizing the studio as a long term business). I quit when my job stopped being dev work and started being round tables about how to psychologically trick players into paying more. Anyway with so much focus on heavy monetization it stopped being economically worth it for a lot of startups to actually make good games when thinly veiled skinner boxes pleased the investors all the same