The fact that you didn't use the term "portable assembler" when saying: "If you take a concrete example where memory is effectively an array and indices are addresses (which holds true for most cases and, in any case is a good example)" doesn't change the fact that the statement makes links to how actual machine memory operates on what you personally think is a usual machine. This is really not a good idea because it encourages people to think of pointers as all existing in the same place and encourages erroneous thinking such as subtracting two pointers to different objects or confusion surrounding why the numbers you get when you `int a; char b; printf("%p, %p\n%p, %p\n", &a, &a+1, &b, &b+1);` differ in separation. Also subtler errors arise such as people assuming that all pointer types are effectively equal as long as you convert back to the correct pointer type when it comes to using the pointer (really subtle issues like people assuming that you can convert `int *` to `void *` safely).

The "very abstract" way C is taught actually prevents people from making such assumptions by not priming them to make them. The fact that people get complacent and start to lean on their understanding of (what they think are) real machines to write C is the result of the bugs I mentioned in the previous response.