Address bar: I know what I want and I want it to only search in bookmarks and history.
Search bar: I don't quite know what I want and I want to open an internet search for it. And possibly give suggestions from actual search results.
Separating the address and search bars is the first thing I do when I set up a new Firefox. I hope it will stay around but I'm somewhat bracing myself for it to go away eventually.
Press space? Not every use case has to be addressed by UI elements, especially when we're talking about edge cases
Firefox (and Edge; don't know about Chrome as I don't use it) still have the concept of "Search Keywords" that you can prefix searches with to get into search modes for against specific non-default search providers. For instance in the Firefox bar you can type @wikipedia and go directly to a Wikipedia Search mode.
> If you have enabled Emacs-style text editing shortcuts in GNOME, they will also work in Firefox. When an Emacs text editing shortcut conflicts with the default shortcuts (as occurs with Ctrl+K), the Emacs shortcut will take precedence if focus is inside a text box (which would include the address bar and search bar). In such cases you should use the alternate keyboard shortcut if one is listed below.
https://support.mozilla.org/en-US/kb/keyboard-shortcuts-perf...
I get it, I'm not the kind of user this article is about. And maybe I'm just insufficiently exposed to the other paradigm to have become "fluent" in it. But I just wanted to point out that there definitely are users whose mental model differentiates search terms and URLs.