Are you sure the IQ scores went out of fashion because people were able to train to get them higher, and not because one of: 1. There are only so many IQ tests

Are you sure the IQ scores went out of fashion because people were able to train to get them higher, and not because one of: 1. There are only so many IQ tests, so people applying simply memorized the one job administered or 2. IQ tests were so effective they prevented nepotism, and people just could not have it Do you have any data to support you point?