Earlier today I asked the question, "Why don't all modern languages support first-class functions?". It was promptly closed. As I explained in the comments, I think it's a good question for someone with language design experience to answer. It's fine if Stack Overflow is not the correct place for it, but if that's the case, where should I ask it?
It's a discussion question, not a Q/A question. Just to dissect a bit:
Note that there are no facts that could come up in response to any of those -- only opinions. There's really no right or wrong answer. Therefore, it's not a Stack Exchange question. Simple as that.
It's a broad and subjective question.
This question can't be tied down to a specific use case or a specific reason - each language designer decided on their own whether or not they'd support first-class functions. The majority users of SO, who are not language designers, can only guess at the reason why more languages (or better yet, why most languages) don't have first-class functions, so it wouldn't work on SO.
I can't think of a site in-network offhand that would allow this question though; I genuinely do feel that you would be better served asking the language designers directly instead.