> "... which may have left those who finished their apprenticeships ('journeymen' in the parlance), stuck in subordinate positions until age and death opened up space in the local guild for a new master."

The "journey" part of journeymen is because they would usually travel around instead of waiting for space in the local guild. Compare the (nominally white collar) postdoc.

https://en.wikipedia.org/wiki/Journeyman#Origin

(I still see wandering journeymen, in traditional garb, from time to time.)