[nightpool]

Yes, the commenter you're replying to is specifically talking to programmers, and tell them, from a programming perspective, not to treat a credit card number as a number. They're specifically trying to draw people's attention to the distinction you're saying they "mix up". The point is—even if you might call it a number, you cannot use HTML's "number" type or any numeric types in popular programming languages for storing or processing this data. That's the entire point of the article