The script writers were so busy setting shipping wars in motion
Playing with Anya/Xander shippers feelings by letting the wedding Day arrive, then Xander leaves Anya at the Alter...
I Want Xander flogged for that scene, personally.
And "Hmmmn lets screw around with Buffy/Spike shippers, and give the Bangel shipepers something o screech about?"
They may not have thought of a plot like this, just pointing it out
Sorry for the rant, just your right it seems very obvious, and would have been better to see Dawn babysitting, then to see spike doing his ... Exercises.
Aside from the cult idea?
Maybe some Vampire approaches one of the Tykes windows and gets out A bunch of flashy and yummy Candy?... all he wants is to be invited in..
so many ways to do things.