I don't disagree with this and it is the product of upwards pressure coming from a great system as well as establishment on top.
I think(?) one of the unique nuances of developing a minor league system well that doesn't get talked about enough (not that I can speak to it at all - I'm hypothesizing) is creating trade capital from non-trade capital sources. If the Brewers can turn Will Childers into a tradeable asset, if they can 'day trade' Tyler Black's hypothetical good May/June stretch, if they can graduate Brian Fitzpatrick into a major league contributor which makes someone like DL Hall or Jared Koenig expendable, etc - you are creating excess system value that can be harvested.
The Brewers haven't been perfect by any means but we just haven't traded a lot of prospects that we have regretted in recent memory and I think that speaks to both the return being optimal but also that maybe we have maximized abilities here that show well on the trade block.