The process you're describing is the exact thing you want to happen: junior developers are trying to learn to write better code. Why should they waste their time researching not their code base when they can instead learn off their code base from people experienced with it?
Because that's what everyone does? You learn by studying other's people work and try to apply it to your own. Painters, musicians, architects, etc … all do it. Why not developers? Instead everyone's rushing to learn React without even knowing the DOM api. Or build a web app with 1000s of dependencies that could be done with a few PHP files. And then they say they need docker and k8s.
The entire debate is over which qualities count as "better". Even "readable" is subjective. Some people love Java with sentence-long variable names. Some love 1-letter vars. Some love 100-deep call stacks, some love flat code. Some love microservices, some love resident call-stacks.
