Ask HN: Why aren't there any “ ” and “?” variants with comma underneath?

I'm not the first one who has proposed the idea[1], but the lack of Unicode support for this, is surprising. I mean, we have the interrobang and all sorts of obscure punctuation marks there. Why have "exclamation comma" and "question comma" been left out? [1] - https://www.huffpost.com/entry/exclamation-comma_n_7710586