That's not in-depth knowledge, that's basic usage. I don't have in-depth knowledge of git myself, most of its plumbing is an opaque black box for me. Less obvious but useful things like `--first-parent` are just one manpage reading session away. If your colleagues are unable to perform some basic rebases to squash away their WIP commits, you may want to help them learn how to use one of the most essential tools in their work. Everyone in your team will benefit.