Math isn't the only class that gives homework. Should Spanish class-time be spent memorizing vocabulary and conjugations, or practicing communicating in the language? Should History class-time be spent reading from the book so you know what happened, or discussing those topics and their implications? Should English class-time be spent doing silent reading, or talking about the books/authors/time periods that you read…
If I work from home for a company, it's not called homework because it is under the same conditions as normal work: there are set hours, I receive compensation, the only difference is that it's not on-site.
So should Spanish class time be spent memorizing vocabulary? No, at least not in large parts, but neither should it take more than the time allocated for the subject[1]. It's nice that we can choose to do it either in school or at home, but the way it presently works, homework takes up more time than it should.
[1] Again, I don't mean allocated class hours, I mean the total number of hours students are expected to work on something. In Dutch terms, SBUs, or "hours the course takes from your life, class and homework and everything together". All courses should have SBUs that add up to 40 hours per week, give or take 5.