As far as I can see a BB and a Headset do very similar jobs and we (generally and excepting the most recent press fit BB’s) expect a BB to be threaded and everyone finds it very easy to fit/replace BB’s with relatively simple and cheap tools.
Headset fitting seems to be stuck in the ‘interference fit’ school of engineering which either involves presses or twatting with a hammer. Both seem to offer opportunity for damaging either the component or the frame and the former needs a relatively costly press to ensure a good job.
Using a headset that screwed into the frame would (with a suitably faced head tube) remove the risk that seems inherent in doing this job, even with the right tools.
What have I missed?