I suspect that in part it's more common because demand for skills massively outstripping supply means that organisations have to put up with ahem personality quirks they wouldn't otherwise tolerate (or would at least avoid).
That said when I first started in IT I was surprised by how few people conformed to the cliched socially awkward stereotype. Yes it was more noticeable than in a typical a cross section of the general public, but I think that the damage someone being a complete jerk can have in a team context means that even given the difficulty in hiring it's selected out to some degree - you've either got to be really good, or at least be able to hide your true nature at interview.
That said when I first started in IT I was surprised by how few people conformed to the cliched socially awkward stereotype. Yes it was more noticeable than in a typical a cross section of the general public, but I think that the damage someone being a complete jerk can have in a team context means that even given the difficulty in hiring it's selected out to some degree - you've either got to be really good, or at least be able to hide your true nature at interview.