I disagree. What it doesn't offer, people will try to do anyway, each in their own ad-hoc way. See how people used to abuse <div> before HTML5 (and still do)

What it doesn't offer makes a significant chunk of content that people actually write and read inaccessible.

For example, the lack of simple text styling makes Gemini significantly less accessible than it could've been. Because now a screenreader will say something like "Significantly asterisk less asterisk accessible" instead of "Significantly emphasis less accessible".

I don't think images can have alt-text in Gemini so that blind users could get info from there.

Etc.

Edit: someone else has a much better answer: https://news.ycombinator.com/item?id=37052729