Although I too think that understanding the Math behind the algorithms is the most important thing in machine learning. I strongly disagree with your point of vue in this certification.
It is for a reason that this certification has the name "Tensorflow Developer Certificate". It teaches you the programming side of deep learning and speciafically how to exploit Tensorflow at its best. Everybody should definitely dive into the math behind deep learning but not with this specialisation It does not mean the learned lesson will be useless.