I have seen some cool blog posts with SVG/CSS animations up-voted on HN. Because you submit links here for the most part, your blog post can still be visible. https://en.wikipedia.org/wiki/News_aggregator

Besides Reddit, I don't think most other mainstream social media works that way.

You can't but you can host them on your own and then put a link to them which is more cumbersome both for the writer and the reader who has to click a different link for each svg (or other asset) instead of just clicking one link to an article which inline them.