With labour parties, I find that there needs to be some sort of reciprocation for them to come across as something other than a blatant grab for free labour.
Among friends or family who regularly socialize and do things for each other, it can work, because it balances out. It can also work for people who have mutually tradable skills - my brother's done this for home renovations, where he has a friend who has X specialized skill and equipment come over and do something, and he does the same for them at some point.
It also works in the case where someone genuinely loves doing the work, and is happy to do it for fun (this is a lot rarer than the person *holding* the party tends to assume), or if someone is interested in getting training in a specific skill.
Even among friends who socialize regularly, if you're constantly being asked to do labour for a set of friends, and they're the only ones in that social set who recruit their friends for painting/sanding/moving/yard work, it still gets old fast.