I never took place on WOTM before, but having looked at the OP I do heavily suspect the topic had something to do with it.

It sparked about no imagination/creativity in my mind. Maybe if WOTM left more vague (or simply less) requirements would take part cause that leaves more theme's and plots available which can draw in more people.

As for comparing this to Spam Adventures? That's spam, they're insanely active simply, mainly because them posting all day and day about basically anything has allowed for an insanely close bit (though exclusive) community, so as a result they are practically always on there interacting with one another, especially flocking to things like that which would involve them and all their friends.