[usrbinbash]

Because naming conventions are important for code reability.

When I look at a piece of code and I see something like "FOOBAR" I can be quite sure that I am looking at some variable in the global namespace. "FooBar" is most likely a class/struct. `foobar` could be a local name or a function.

Sure, these are conventions and don't need to be observed technically, but they are, because they are useful, same as it's useful to name counter variables in loops "i" instead of "localLoopIterationCounterVariable".

Oh and of course there are languages where case actually does matter syntactically, like Golang.

All of that flies out the window in a language that simply ignores case. And it is at this point where I pose the counter-question: What makes ignoring case in a programming language useful?