Comment by ajross
True enough, but it does make for good practice with the index and splitting workflows later on when you need to clean it up.
I think there's space for "git add ." as a didactic step. It maps cleanly to the most obvious way to understand a commit, as "here's what I've done". Bootstrapping from that to an understanding of "commits as communication with other developers" will naturally happen over time.
Is not very compatible with printlog-debugging. I'd rather encourage devs to prod around as they go if it benefits them, which causes grief for either them or reviewers in the end if they've internalized what you just said.
Explicitly adding internalizes a personal review process as inherent part of the push process, instead of something you attempt to force on top later.
It's better with a collaboration workflow that limits the span of time with expected discipline, imo.