It's not unique to IT, but it does seem to be a bit more acute there, likely due to the fact that in terms of business organization, IT is still very new as compared to functions like HR, Accounting, etc. Many roles that were once rolled into one position (because that was pretty much all that was needed at the time) have diversified due to the maturing of the IT field as a whole.

Part of me wonders if there isn't some marketing strategy with regard to job titles as a bit of a psychological "filter" for applicants.