That's crazy. Part of me would like to put SOME blame on these people for not showing up at 3 (when I believe event ticket holders can enter DCA), but I suppose you never know with Disneyland Resort and its fans, and perhaps the wait to get in was just as bad then. Perhaps there was truly no way to avoid the madness in this scenario.
That's why I ALWAYS spring for whatever sort of early access is offered for Halloween events-Boofets, Stay n Scream, Early Entry, just showing up super early if there isn't an upcharge or park closure before the event proper starts, etc, because in addition to being closer to everything when the event begins, there is a 100% chance that my experience will be better (or at least, more pleasant) than people who have to wait crowded like sardines for a long time just to get in when the event officially begins.