Fair enough. But notice: systems tend to expect that humans interacting with them observe basic rules. "The capital/lowercase variants of western alphabet letters are represented each as distinct character" is one such generic, basic rule with computer systems. Especially if we zoom out of FS's into a broader context (http, json, programming languages, etc) — you can't deny it; it's a fact.

We do have the options to ignore the fact and say "What bytes? I don't care. Guess what I mean, and lie to me as well as you can so I can stay happy in my ignorance" — but, see, coordinating good support for that isn't easy. Minor wrinkles in it continue causing burns, sometimes RCEs. Maybe "doing in Rome as Romans do" isn't such a bad advice after all?