It is more a matter of having all necessary skills aquired. You need to understand coding, lots of vector math, 3D asset creation etc…
Those are skills that people usually posses to the required extents around 30, ie after getting a degree or teaching themselved. You will not see many devs working in <25 years. Most are 30…40years old. I mean you sure can texture an object in Blender at younger ages, but most likely you will not be able to convert Euler angles into quaternions, or know in depth vector math and so on. Getting the complete skill set from texturing to vector math to coding basics hardly happens before 25.
In some sense, if you go for a full game, you need practically all skills that you need for most other software/App development as well.