I once read that the academic social contract before the 1970s was that an advisor would not accept a graduate student unless they were sure they had a "place"

I once read that the academic social contract before the 1970s was that an advisor would not accept a graduate student unless they were sure they had a "place" for them lined up, i.e., in another institution. I don't know how that could have worked, but it speaks to the difference in social contract prior to when graduate students were treated as exploitable labor with no actual academic prospects.