Bring back tab-to-search

Start typing the URL of a website. When a suggestion appears, press "tab" to search the website:

That is/was tab-to-search. I'm not sure I should speak in the past tense, since it still works for some websites, and you can still manually activate it for every website, but it doesn't work by default for every website that supports opensearch anymore.

Does this matter? Can't you just use google for everything? For example instead of searching HN with tab-to-search can't you just add "hackernews" to your google query? That might work for HN (though it lacks certain options to sort and filter results, is not live and not as convenient) but it doesn't work for your notes, emails, messages …