This is false. I
have learned the basics of assembly without knowing C first. My experience before learning assembly was: Java, Python and some Objective-C (without knowing pointers). So if your point is that you need to learn programming first, then maybe that is true but I highly doubt it. But I can't refute that with my own experience.
Here wa my roadmap:
(1) I first learned assembly by learning computer architecture from Tanenbaum's book -- Structured Computer Organization -- and related course at the Vrije Universiteit Amsterdam. This taught me a toy architecture (Mic1) but it give me a rough idea of how assembly worked.
(2) Then, later I took a course in binary and malware analysis and all that we were required to do was to read x86 assembly in IDA and interact with it via GDB -- and using the command: layout asm, which gives a layout for all the register values and upcoming instructions.
And once I have a debugger available and understand it well enough, I can learn quite well since I can make little predictions and check if they are right or wrong, and so on.