Teaching cursive illustrates the same empty headed mindset that has had students learn the nonsense that is prescriptive grammar.
Let's teach it this way because that's how it was done in the past.
Teachers come into the classroom and tell students how to do something they don't do themselves, teach them things that reflects reality not at all.
I can remember practicing my signature, my own signature, soon after the cursive lessons started. Out the window went some of the cursive letters we were taught.