Not necessarily. I agree that having values dictated by fiat is a recipe for disaster - such arrangements are bound to get corrupted over time. But on the other end of the spectrum, there is some sense of social value - a sense in which e.g. garbage collectors, firemen and doctors do more socially valuable jobs than athletes and entertainers. A sense that's easy to convey - imagine if suddenly, any one of the former three occupations disappeared; the death toll and suffering would quickly overshadow the largest of wars. Meanwhile, even if both of the latter occupations disappeared, the culture would be a bit poorer, but the society would function just fine.
Unfortunately, it seems that this concept of social value is very hard to robustly define. And if we can't define it, effectively optimizing for it is pretty much out of the question.