Who wants to be HoD? Not a reluctant temporary servant, but someone who wants to be Dean, which is in turn someone who wants to be PVC, who in turn wants to be DVC, and ultimately after the big prize of the VC payout.
At every stage, selling out the university is rewarded.
Sadly, all academics today know that “a management role” on your CV is the only way to get beyond SL.
My father was a STEM academic: in his day HoD was an irksome, temporary role.
Now everyone longs to be VHoD, Director of Learning & Teaching (DOLT, seriously!) or whatever.