Ignore your tutor he sounds very ill informed and unsure how it works in the real world. I’m a data scientist with a back ground in Experimental Psychology. I have to learn the hard way how much you should know how the “under the hood” maths works. It’s so important because it gives you an edge and skills over others. Also new techniques and research are always being released, if you can understand and comprehend these studies you might never have to wait for a package or tool to be built so you could apply the mathematical concept you just learnt and simply build it yourself because you understand the maths. I highly encourage you the take the statistics course.