If there are generally decreasing returns to measurement of a single variable, I think this is more what we would expect see. If you've already put effort into measurement of a given variable it will have lower information value on the margin. If you add in enough costs for switching measurements, then even the optimal strategy might spend a serious amount of time/effort pursuing lower value measurements.

Further, if they hadn't even thought of some measurements they couldn't have pursued them, so they wouldn't have suffered any declining returns.

I don't think this is the primary reason, but may contribute, especially in conjunction with reasons from sibling comments.