I think I agree with Carmack on this. I'm hyper aware of case now, but this was probably the major cause of errors for me when learning (didn't help that tooling was less good then, so there were no linters pointing out my errors).
I guess for me it's one of those things I got tripped up on initially but came to appreciate later. It taught me how to be more precise about characters and reasoning about them in code.
There's also cases where case sensitivity should matter in naming in my experience, and it's not possible without it.
Personally this preciseness is just a distraction, but it sounds like you have learned from the constraints and can now take the training wheels off again.
Very curious about those cases, yet to find one myself that was not because of a bad design decision. Though I am also very big on the idea of `ambiguous grammar, rigorous implementation`, for natural language too. (Toki Pona is a somewhat extreme example but the contextual grammar, and holistic minimalism is fascinating)