5 credits/year is a full time undergrad course load - why would a full-time 2-year masters require the student to earn 5.0 credits to graduate?
It's not clear here if you think a 'half-load' of courses is too high, or too low for a Master's. 

Here's a perspective from my university. Here, your course work serves two purposes in your masters:


Course work is there to rectify gaps in your background. As a school with a huge international student population, we have a huge amount of variance in skill-sets. As a result courses are there partially in order to help make up for missing background, or to get the students onto more common footing. 
Introduction to topics. Here you're admitted without having to declare a supervisor or a topic. The first year of courses serves to introduce students to topics and professors-- possible supervisors. 


After two semesters, most students have paired off with supervisors, and have started their research, which will dominate their time for the subsequent 16+ months, until they defend their thesis.