Haughtney1
Psychometrics have pros and cons, not just in airline use, but generally.
I can't give you a straight answer to your question, only my own opinion, which you may accept or reject as you wish
Selecting the right person to fit into an organization is challenging and pyschometrics MAY help to get someone close to the profile.
For example, someone with a strong preference for introversion (a preference to take in data, process it internally and draw their own conclusions) may not make the ideal member of a team in some circumstances and psychomtric testing (backed by other technicques, such as observation of participation in exercises or even plain old taking up of references) can help to recognise that preference - by the way a preference like that could be a flaw in one role and a veritable strength in another, so pyschometrics shouldn't be viewed as the tools of the devil nor as a panacea for all evils.
People are becoming more skilled at "passing" pyschometric tests (presenting the desired profile by manipulating their answers and some tools, e.g Myers Briggs, are quite easy to manipulate.
There is no substitute for skilled human intuition (IMHO), the tests should simply support the interpretation of whether someone is right for a particular role, one of the reasons why a sim ride might be very enlightening if the "simee" regressess from their interview behaviour to their normal behaviour, under a little pressure.
As for weeding out, well I suppose if you needed a high level of mathematical reasoning and a test said that someone did not have that, it could be used in that way.
As I say, I can't speak for others, that's my own view - I hope that I've at least partially answered your question.