Everyone and their sister wants to be the one that does the pretty graphics and UI with Unity or whatever. Nobody wants to be the one who does the backend code that actually makes the game work.
It's actually challenging when you work with games that might have a million daily users or even more. If it's a competitive game, people will try to cheat and you can't trust anything the client sends you. The code also needs to be cost-effective to run, if your game makes $10k a day, but the backend costs $5k a day to run - that's kinda bad.
Also especially mobile games need a custom frontend for customer service so they can do refunds, check player purchase history etc. Those are done with JS and Python etc.
Source: Moved from traditional tech to making CS tools and backend for games. My salary went up hilarious amounts, as did bonuses and options.