you’d never have player movement in the GameManager class
You want to bet? (Source: I teach game programming on a college level.)
But yeah, your comment about the gear icon is sadly more true than people may realize. Game developers do questionable things. => Engine developers cater to people. => Students argue that if something is supported it can’t be that bad. Sometimes it feels like fighting windmills.
At my first job I was working on an MMO and we had a DatabaseManager class with 10k+ lines of code. Less than the first 200 lines actually used any of the members of that class.