This study is just asking managers, they didn't talk to devs. Also how is it a monopoly when 80% expect to be using non steam distribution channels in 5 years? Maybe I'm missing something because the source study isn't available without giving them your name and email but their stats look contradictory to me and their method is... Well corporate managers aren't really devs IMO.

https://rokky.com/pc-game-distribution-report-2025