[RealCodingOtaku]

Font customization is need to emphasise, it helps the reader understand the sentence better, other styles such italics, underline, and strike through… would greatly improve understanding the context and increase readability, it's just a matter of good typesetting.

Inline links also help with the same, people who dislike it should be able to move them out of the context (like some terminal based browsers).

I don't care about image, video etc, they can just be a link to the resource if/when needed... given alt text/CC is supported or accessibility. Same for color coding stuff and CSS, users should customize their client for that if they want to, not the server.