I'd argue that manually adding each site individually is not "even simpler".
Does Chrome do it for random site searches? Not for Google properties.
Re:Firefox 64 Released
by 8_hours_ago on Tuesday December 11, 2018 @06:50PM
(#18660116)
Chrome automatically adds sites if they have an OpenSearch description document:
https://www.chromium.org/tab-to-search
Firefox requires the user to add the search engine manually: https://support.mozilla.org/en-US/kb/add-or-remove-search-en...
[1] open youtube.com
[2] right click on the search bar and select "Add a keyword for this search"
[3] in the dialog enter the character "y" as the keyword.
[4] done!
now to search youtube from the address bar just enter y followed by the search terms!