The above explanation is great but I think the example you selected (git) is rarely the right thing to choose as for most companies git isn't where the money comes from (notable exceptions are companies like GitHub or GitLab). Sorta like the difference between working in the IT department vs Development (for a software company).
Maybe a better choice is something like CSS: there's actually a lot to know about it and a lot of companies need people who are good at it for their core product (even though it's not as deep a topic as say being very knowledgeable/skilled in functional programming).
Maybe a better choice is something like CSS: there's actually a lot to know about it and a lot of companies need people who are good at it for their core product (even though it's not as deep a topic as say being very knowledgeable/skilled in functional programming).