Speaking in so much the abstract that it becomes absurd (which also can be used to prove your point, but bear with me here), since `size_t` is required to hold the size of any object, and a turing machine has infinite memory, then size_t would also need to be infinitely big, and `sizeof(size_t)` would be a constant returning infinity.

So, I don't think it having to be a constant is a problem as much as having to deal with infinitely big numbers inside of infinite memory (which may or may not be a contradiction, depending on axioms used to define a turing machine. I still need to work my way through annotated turing).

Of course, things do get a lot simpler and grounded using IO functions like you said earlier.