Yes, I know that the h-index suffers from some limitations, much like any other quantitative index. I know that no one’s research or professional activity can be summarized in a single number, that evaluating a scientist is far more complex an operation than that. Nobody has ever suggested that the h-index, or for that matter number of citations, or publications, or invited talks, or what have you, should be the only, or even the main way of evaluating a scholar, especially for promotion and tenure purposes.
… some of us are very unhappy with a scientific establishment that evaluates scholars, especially young ones, almost exclusively based on their pedigree and/or on the opinion of few “prominent” scientists, all based at even fewer “prestigious” institutions. This is, in my opinion, the main reason why so many faculty openings (e.g., in condensed matter physics) go unfilled every year, even in the face of a supposed glut of qualified applicants . Departments all go after the “few excellent” applicants, all from the same factory, and since these few elects can not take more than one job, positions remain unfilled, as no chance is given to outsiders. As a result, departments age, research activity languishes and young people turn away from the field.
This is a bad thing. It is bad for science. And it is stupid.
The same mechanism largely explains why the same people are always invited to give talks at conferences, receive the lion’s share of grant funding, win prizes and so on. It is, in essence, a self-fulfilling prophecy. We need to break this vicious cycle. Science is not, cannot be an “ol’ boys network”.
Numerical indicators such as the h-index, while not themselves immune from bias (reflecting the same dynamics described above), at least might offer young scientists whose records are placed side by side those of competitors with more conspicuous pedigrees, a fighting chance.
The h-index correlates reasonably well with overall scientific achievement and productivity, and while it can never be the one and only thing to look at, it might give an evaluator a reason to take a second look at, and examine more carefully, the record of an applicant whose pedigree may not automatically brand him/her as “stellar”. If you take away all numerical measures, then all you are left with are the “unmeasurables”, and those lead to the same outcome, every time.
So, to my younger colleagues out there, looking for their first faculty job, bitching about the h-index but also complaining about the “powers-that-be”, or lamenting all sort of social conspiracy if they do not land one, here is a question for you:
“Would you rather make it all about where you got your PhD, whom you know, and what so-and-so says about you ? Or do you think that maybe, just maybe, looking at some numbers might help too ?” .
 To be sure, I have personally never believed that such a glut existed — but I do not believe that there is any shortage thereof either.