It is wrong to suppose that if you can’t measure it, you can’t manage it – a costly myth.
It wasn't Drucker either.
https://medium.com/centre-for-public-impact/what-gets-measur...
This whole mindless must measure, must measure mentality has been criticized since the 50s. Measurement is a tool. There are many tools.
The problem is that people tend to think that all measurement is necessarily quantitative. I think that this might be a version of the streetlight effect? Quantitative measurements tend to be much easier to collect and analyze than qualitative measurements. Oftentimes you can let it all run on autopilot, whereas doing good qualitative work always requires concentration, effort, and expertise.
That would be true, if measurement was free. It never is, and it often is quite costly.
I suppose this is part of why "chaos engineering" has gained popularity- introducing artificial disruptions at a known rate makes it easier to quantify the impact of otherwise-unusual events.
That wasn't Deming’s position, Deming was pretty strong on the idea that there are measurable things that it is not cost effective to measure.
A big contribution of Deming’s here is the importance of understanding uncertainty in measurements relations between them to understand the degree of control.
One issue is that some things, like vulnerability to supply chain disruptions, are intrinsically harder to track because they are based on rare occurrences. Thus, they will tend to get sacrificed in favor of measures which are more frequent, leading to an emphasis on short-term strategies.