What things to learn are more important for "engineers" than using VC messages and history for communicating adequately (including communicating with themselves in the future) and using VC merging, staging etc. to put source code in a good state that they intend to build, share and archive? Irreproducible or incomprehensible work is worse than nothing.

That’s akin to saying the most important thing for an author is to use a word professor correctly.