There are a couple I have in mind. Like many techies, I am a huge fan of RSS for content distribution and XMPP for federated communication.
The really niche one I like is S-expressions as a data format and configuration in place of json, yaml, toml, etc.
I am a big fan of Plaintext formats, although I wish markdown had a few more features like tables.
Would you have to do that for every letter? I suppose a “bold-on/bold-off” character combination would be better/easier, and then you could combine multiple styles without multiplying the number of glyphs by some ridiculous number.
Anyways, because markup is already standardized, mostly. Having both unicode and markup would be a nightmare. More complicated markup (bulleted lists, tables) is simpler than it would be in Unicode. And markup is outside of Unicode’s intended purpose, which is to have a collection of every glyph. Styling is separate from glyphs, and has been for a long time, for good reason. Fonts, bold/italics/underline/strikethrough, color, tables and lists, headings, font size, etc. are simply not something Unicode is designed to handle.
Yeah, had the same thought, edited already.