While I do agree with the latter 2 points, (can't multi-jump, hard to memorize), the assertion It follows the order of the DOM elements and not the visual position of these elements on the page, which means that it uses the HTML structure (not user-friendly), but it should go after the layout position (spatial position); Isn't quite true - all HTML elements support the "tabindex" attribute[0], which can be used to se…
For example on Wikipedia (and in MediaWiki in general), Alt+Shift+F is search (I guess F is for Find; S is already taken by Save anyway, for people who edit).
There's a lot of them, though most of them immediately navigate you rather than focus an element - https://meta.wikimedia.org/wiki/Help:Keyboard_shortcuts