Your bags can't ship if you don't board your first segment. After that they may take a different flight. Happens all the time in IRROPS. Imagine your bag missing a flight, if the rule was as you described it could never catch up to you (or you would have to fly back to get it).

As for the (not directly asked) security implications, IMHO this (and many other) rule falls into the annoyance without a security benefit category. So I don't really worry about loopholes.