It does affect identifiers, built-in keywords and type names in the same manner, though it is completely beyond me why anyone would write 'tY_PE Position = tUPLE[x, y: iNt]'.
If we are going to dismiss any nontrivial behavior as "sure very simple" then sure, having two distinct incompatible ways to write get_name (or getName) looks better.
It does not "randomly" not affect first character. Most style guides for camel/pascal case treat first character differently, with types being capitalized and regular variables starting in lowercase. Making whole identifier style-insensetive would significantly reduce number of possible names. So this rule makes 'building' and 'Building' different, but at the same time does not differentiate between 'get_name' and 'getName'.
> Yeah because nobody ever imports code from other projects, copy/pastes from StackOverflow etc. /s
I don't understand your point (even considering /s) - if I do import code from my other projects or copy-paste it from somewhere it simply doesn't matter to me what style they used - I'm not required to fix copied code, or adapt to the style my dependencies use.
> So why do you need case insensitivity??!
If their code gets into larger ecosystem it will not affect anything else, or at least it's effects would be minimized. It is a win-win solution - library author uses their preferred style, I (and everyone else in the ecosystem) stick to common convention, and everyone bis happy.
> Trust me this is a decision they will regret.
I've been using nim for multiple years now, and I have never seen anyone actually regretting this. Of course, when new people come to the language they sometimes are really surprised by this, but rarely ever complain about this in the long run.
EDIT: forgot to mention that nim is more than a decade old language, and "decision they will regret" should have happened years ago, yet it does not seem to be the case.