That seems like about the right proportion to me - struct solves a much more common problem than restrict does. And to be fair, it is a lesser known feature. But user-the-name is implying that restrict is somehow difficult to use or understand, which I don't agree with at all.
I checked on grep.app, there are 10k results for `restrict` for C code, compared to 700k for `struct` (I know they're not directly comparable but that gives an idea.