Of course the other party analogy is
I want a Referendum discussion party. I am going to invite, immediate family, and perhaps some friends.
About 10 - 15 people Max. My house can easily fit them in, I know and can afford food and drinks for that number. Good debate, arguing
and a sweep steak at the end.
Dh says, some of his friends from work would like to come, and he hasnt hosted them for a while, so we invite them, another 7 people. One asks if he can bring his partner, we say YES, the more the merrier, they all want to bring partners, fine. One says, - how old are our dc, can he bring his along? We say fine. Suddenly numbers are growing, but its still manageable.
We can still fit people in, feed them etc. Then inadvertently mention it to neighbour who would like to come, cant say NO, they come and chat to other neighbours who also all want to come.
We are now worried about the whole thing getting out of control. How many numbers are coming now? Can we actually afford to feed this many people, let alone squeeze them all in the house? We don't personally know many of the partners or their DC or neighbours partners, what if it gets very heated? Will fights break out? We can't afford alcohol for everyone and we only have one Loo! 
We decide to cancel the whole thing, because our house is too small and we do not have enough food, drink or facilities to accommodate so many people and we don't know exactly who will come.