And to add to your point, in my experience I've had "long-lived" scripts that the flags change meaning over the years. This is extremely rare on base-level installs, but frighteningly more common on the inhouse-programs I've had to deal with.

The long flags are less likely to be changed over time. The script will usually fail gracefully and I don't also need to relearn what I was thinking 25 years ago when I first did it. (long flags are like in-command comments too)

And as others have pointed out -v(ersion) or -v(erbose) can happen too.