I had a chat on the topic with a game dev. Essentially, the argument was that games tend to have original UI and interaction models. For example, a web dev can get away with a <Button /> and a CSS/JS framework and make spectacular UI but when it comes to games the creatives would demand that button to be designed to match games concept, therefore for a game dev to build a button it may require to deal with all the styling and button states that a web dev would never touch(because it is taken care by the browser or the UI library).

An average game dev would have much deeper knowledge on the stuff they do than the average dev that build corporate software since the game devs would de bespoke work every time. Sure, they also have assets etc. but in the gaming the originality is much more important since the product itself is meant to be enjoyable, not simply a medium to accomplish something else(like ordering pizza or keep track of payments).