What did this guy think was the purpose of threads before multi-processors were common? What does he think is the point of green threads? Fibres? Why does he

What did this guy think was the purpose of threads before multi-processors were common? What does he think is the point of green threads? Fibres? Why does he think some languages only allow one thread to run at a time but still have threads? Answer to all these questions is: he’s mistaken about the original purpose of threads.