New devs - especially those coming from bootcamps (I say this without judgement) - mostly start with practical skills. Industry-standard ways to just get things done. That's how you get a job, that's how you get off the ground. This goes beyond source-control; languages/frameworks, tooling, etc. You enter the territory - with your finite bandwidth for learning - where it's most immediately useful. And then over the years you move out from there, incorporating more and more nuance and detail and auxiliary knowledge.
There's no need for moral panic. "Where it's most useful to start" has shifted, sure. But that's natural; I don't think it's a new phenomenon or in a fundamentally worse place than before. GitHub is a higher-level tool that makes you dramatically more productive than raw git on its own. The details will be filled in as they work their first job.