What's the relation between Halloween and Bitcoin?
An easy way to earn Merits.
The last pizza challenge
[1] last time added a big boost to many users and is considered the ideal place for alt-accounts farms.
There's no doubt about it - especially if a newbie asks why the same contest wasn't held this year. Contest thread like this are abused by some users as a way to easily earn merit - in fact I wouldn't be at all surprised if they were just doing it for the sake of merit and joining signature campaign.
Halloween contests are not mandatory - but are certainly expected by some people with good skills. Some people abuse it - others really want to win the contest without thinking about how much merit they can get.