alt Hacker Newssharing images and other media is vital in most groups where i participate. we don't just socialize. it's not like HN. we actually work on stuff. and very often images are needed to convey certain information.
though even social channels work better with images. my family channel would be very limited without images. most of what we talk about is things we see, and can share images about.
emoji reactions are another matter. but given that it is possible to just use unicode emojis, i think that reactions reduce clutter.
Social media communities adapt to the constraints of their platform or don't use it. You seem unaffected by the inability to share photos on HN, indicating that's okay for sites that want to be patronized the way HN is. It wouldn't work if you wanted to create a meme channel, but HN doesn't want to be a meme channel and neither does IRC.