I fully agree. But the point about the utility monster concept is that their marginal utility derived from resource allocation has a far higher multiplier than our own marginal utiliy of the same resources, which is additionally diminishing as we get individually richer. Less than 1 != zero.

Well, even if the utility monster is like e^e^e^x, the weight could be like log(log(log(x))), or just 0. At any rate I don't find myself inclined to make one (aside from curiosity's sake) and mathematical utility functions seem like they should be descriptive rather than prescriptive.

In principle, the same could be true of utility monsters once they are no longer hypothetical, and exist in forms which are emotionally attractive to humans.

We might make cute virtual pets or even virtual friends, but I still not going to give them a bunch of money (etc.) just because they would enjoy it much more than me.

edit: In fact I'm leaning towards the idea that in general, a utility function that values others' utility directly is not safe and probably not a good model of something that evolved. (And also seemingly has loop problems when others do the same).