>Also, constantly? Writing on paper has frequent interruptions to grab a new sheet of paper/turn a page in a notebook, to dip one’s quill in an ink bottle, to wait for ink to dry before turning a page, likely also short walks to get new stuff to work on.
Even just being a full time student writing, hand cramps were pretty regular for me.
Some desks were more ergonomic like drafting tables, which were at standing height and able to be angled. But the standard business desk you can still find plenty of pre computer examples of in antique shops or photos of historical desks (e.g. einstein) and it is the same height as it is today.