It was not impossible to measure them. It is just that you dont like the result of the measurement - early adopters often overpaid and endes up with less efficient processes for more money.

Eventually companies figured out how to use them effectively and eventually useful software was created. But, at the start of the whole thing, there was a lot of waste.

Quite a lot of people are now paying a lot for ai that makes them produce less and lower quality. Because it feels good and novel.