I would like HTML to support Apache-style server-side includes natively.

[WebWeWantBot]

The lack of native support in HTML for including partials like nav menus, headers, footers, etc. makes it necessary to use static site generators, server-side programming, or JavaScript for client-side includes that slow down page rendering. For personal website operators using free hosts like NeoCities and NekoWeb, JS is usually the only option for reusing snippets.

I wrote about this in greater detail back in 2023 at https://starbreaker.org/grimoire/entries/html5-needs-partial-element/index.html

As noted, I get around this by using sed, m4, and hxincl in the shell scripts I use to build my website, but this might not be an optimal solution.