That's because past performance is typically a much better predictor of future success that any psychometric test.
The Chairman of the Association of Business Psychologists in Europe has been highly critical of the tests and UK's Chartered Institute of Personnel and Development have recently reported a 22% decline in companies using these tests in the last year alone.
A candidate's ability to perform and indeed probability of success seems to be uncorrelated to the results of these tests. Besides, always hiring based on test results means a type of intellectual staleness could creep into an organisation. More companies should look for those extremes in profile and manage them - it's often where true talent lies.
Over reliance of psychometric testing in corporate SA often results in the best candidate not getting the job - even when the candidate comes with a stellar track record and is clearly the best person for the position.
Companies that are concerned with the psychometric results of an otherwise outstanding candidate should rather to think about developing that person's weakness than dismissing them as unsuitable.
When one of the personality 'quotients' does show up some idiosyncrasy of behaviour, it does not mean the candidate is completely unsuitable. It may mean they have some sort of personality trait that they have overcome and still perform amazingly well - and that nearly all people have a statistical quirk.
Tweaking the skill set of an already great candidate will result in an exceptional human resource for a company as they're likely to be hiring an unusual set of abilities and an unconventional thinker.
