As for everything, it depends. It reminds me of a young office clerk who was helping in the IT department. After a few month she decided it was more interesting to do network administration, but she entered the company with a generic diploma and on the salary grid there is no path between office tasks and IT. She could have argued that she was already doing good enough in the IT job and thus was qualified for the position, but really from an HR point of view she could be BSing them as well, as there is no fast and simple measure of efficiency for IT administration.

The easiest path was to get a Microsoft certification and just apply internally for a job in IT. That went really smooth from the HR point of view, and she recognized earning a ton generic knowledge letting her understand better what she was doing.