If that truly was a joke, it was in poor taste and very unclear.
Your method of 0-10 is not “essentially” the same as a pass/fail system, as it’s not a pass/fail grading. By definition it’s a graded system. Homework assignments (not projects, mind you) shouldn’t be quality-graded, because their use is supposed to be as learning aids and not as student quality measurements. Please don’t misunderstand, I appreciate the effort you’re putting through for your students. However, claiming that most of them make As, to me, is irrelevant. What I truly cared about in school was whether I learned. The grade was secondary (though it usually followed), which is why the pass/fail homework assignments were so helpful–they allowed me to learn without the worry of a grade. Granted, we did have more quizzes in those classes, but if you did the homework with the goal of learning, you were ready for the quizzes.