"accomplished a degree in a host country and obtained a relevant job offer thereafter" is a very good proxy for a lot of desirable properties in immigrants, at least in Canada (per official statistics).

Besides, foreign education credentials and work experience can be very easy to fake depending on home country, so it's understandable that it's worth less in the eyes of immigration systems.

In Canada we have lots of foreign students, and while there are some issues (nothing is perfect), they pay much more than domestic students, essentially funding the higher education institutions. Education is some of the best things you can export, if done properly.