See e.g. wonderfully named "A Simple, Possibly Correct LR Parser for C11" [0], specifically the opening discussion of the ambiguities in the C grammar. Never mind the semantics, which are quite divorced from the underlying hardware! I mean, PDP-11 had a carry flag, a double-wide multiplication instruction, a combined divide-with-remainder instruction (just as x86 does) yet those are unexposed in C.
Yes, but maybe I want to shoot myself in the foot or am willing to take the risk, it's my computer and nobody can tell me what to do with it. That's why I like C. I've been writing Python for almost two decades now, all the new languages are trying even more to tell me how to do things or that I'm doing them wrong, screw that, I don't want to be coddled or patronised by the language I'm using, I'm writing C.
I think parent means simple as in the language has very few facilities and the ones it gives you are very barebones (hence simple). C is simple in the sense that a screwdriver is simple compared to a power tool.
It doesn't mean that it is simple to use correctly. An expert might be able to accurately judge the torque achieved by hand, but a beginner can easily under- or over-torque things. Etc...
Frankly this is why I have trouble taking all this C advocacy seriously. Do managers really want their engineers using C? I understand how it can be pleasurable in the way that listening to vinyl is pleasureable. But my undersanding is that it takes years and years of experience to not make catastrophic errors in C. And that's a lot of risk.
[0] https://hal.science/hal-01633123/document