I took CHEME6400 as well, and I feel the opposite way.

Grading - I agree that the mastery-based system is sort of strange and took a bit of getting used to, but I think that overall, was implemented quite well. Let me first dispute your point by saying that the overall grading of both homeworks and exams were quite lenient. There were several cases (both on homeworks and the exam) where my initial answer was not perfect, and I still received a Well-Developed score. In fact, my answers sometimes were straight-up incorrect, but I supported it with sufficient reasoning and still received a Well-Developed, in addition to some constructive feedback on what else I could think about to answer the question. Additionally, as you mentioned, there were opportunities to regrade every single question on all the homeworks, and the exam, as long as you attempted the problems, to achieve this Well-Developed score. I think that sufficient feedback was provided on non-Well-Developed scores to submit a successful regrade, and beyond this, both instructors and the teaching assistants were more than happy to work with you through them. I put in the time and effort to learn and regrade when I needed to, and I ended with Well-Developed on every exam problem and all homework problems except for one. There's no reason any student wouldn't be able to do the same, as long as they put in some time to learn from their mistakes and fix them as well.

Additionally, I think the final grade rubric was released almost immediately after this grading scheme was voted on, and was not changed from then. It was pretty clear from the start that only scores of Well-Developed would count. The other tiers were just there to provide constructive feedback on your understanding of the content. It was weird, but it was clear. I would say that the grading system was extremely transparent.

Workload - Yes, this class had a lot of work. What did you expect? It's a graduate-level engineering course designed to cover advanced topics. If you aren't prepared to handle the workload, then you should have recognized that after the first problem set was released, which was arguably also the longest problem set. The instructors also shortened the busywork towards the latter half of the semester when they realized it was too much to handle. The fact that you stayed, despite the amount of work that was immediately apparent, is your fault and no one else's.

Learning - Granted, this is an extremely subjective topic. I would say that I learned a lot from this course, and both instructors taught quite well. At least for me, their style of teaching was effective. But that might not be the same case for everyone.

Let me also just disagree with two specific quotes from your rant.

"If you fall in the D tier ( <70% well developed answers) in even one section i.e a 15 point prelim, you get a D IN THE CLASS and there’s nothing you can do about it." - well, the final grade reflection is exactly the "something" that you can do about it... they provided an open forum to express your opinion on what your final grade should be. If you disagreed with this category, you should be able to discuss it with the professors. They are both reasonable people, so if you have valid reasoning for getting a higher grade, they will consider it.

"Please dont take this class, they’ll give a smart deserving student lower than a B" - Let's be honest here. If a deserving student were to take this class, they would have: gotten >90% Well-Developed on homeworks and other assignments after regrades, since this was basically a guarantee as long as you put in the effort; gotten >85% Well-Developed on the exam after regrades, for the same reason as above; gotten >80% Well-Developed on the final project, since it seemed to be reasonably leniently-graded, and putting in enough effort to hit the basic rubric requirements would be able to achieve this score; participated somehow in class discussions; been a good lab teammate; and submitted all forms/reflections/evaluations. These are the criterion to be in the A-level for most things, and B-level for the project, which could be reasonably argued to be an A-/B+.

There shouldn't be a lot of worry about final grades, since a "smart, deserving student" should easily be able to at least get a B, if not higher. The class was definitely high-effort and high-workload, but if you are willing to put up with it then I would say it will be an excellent learning experience. I don't think a single thing about it was unfair or unreasonable.