Every approach is different because every group of kids are different.
A party for your kid and a few friends (that are all staying/camping out) where there's going to be some drinking isn't the end all be all. The problem is there were an estimated 45 kids. That's simply unmanageable for two parents.
As long as you ask the other kids parents if little Johnny can have a few beers, and they agree as long as its contained and semi supervised, then no big deal, IMO.
45 kids? Not me. 25 kids? Not me. 5-10? Preferably 5, and only if they were well known.