>My point is, are /c/, /h/, /l/ and /s/ absolutely necessary?
It's not wrong that u could post the same contents to Off-Topic
But they are easier to use like an image posting board, when Off-Topic is much more chatty (not to say chatting isn't allowed on these boards)
It's thus a closer experience to Japanese boards where you could just post the images as succeeding threads if you wanted to.
In fact, I wouldn't be able to link Heyuri with much of the Japanese sites we're linked with or that I could share Heyuri on, if we didn't have dedicated 3D Girls board (linked on https://www.toukougazou.net/) or 2D Cute board (required for http://moe100.com/) etc.

>There's nothing there that one couldn't get from a visit to gelbooru, and in both greater quality and quantity, for that matter
If nothing else, I think posting images on an imageboard and viewing what other people using the same site wanted to post is a fun experience in itself