I agree with -Jovian-. Reason for that is some of us have not been playing in an age for a year or even months to build up these millions of supplies and coins some seem to take for granted. Some of us have been playing in a new world for a week or even days and we get the same quest requirements as people who have been playing in an age for a year or more. 5k+ supplies? I have half that, and impossible to make that amount within the event time limit, regardless of how many supply buildings I have, which is already most of my buildings. Not to mention you get daily quests asking for supplies, opening the tech tree wants supplies, building new buildings wants supplies. It's a valid point, that people who are new in any given world are pretty much by default unable to progress in the Halloween event. If you disagree, start a new world and try it!
Edit: actually I have 1473 supplies, so would need to make 4000+ more within 20 days and spend them on nothing else, as well as spend every waking moment doing 5min production runs on every supply building I have. If you could buy supplies with diamonds or transfer FP into supplies I might even consider that, but you can't.