There's no excuse for not making search engine management as simple and flexible as Firefox does, especially on the desktop, but I appreciate the hoops you jump through to keep hacks available for browsers with less user choice.
Even Firefox has its issues - they don't sync search settings along with everything else, and the reason is they're worried about interfering with paid search defaults on new installs.
The last time I checked (this may have changed), Firefox also tags the default search engines with URL query parameters indicating that the search came from Firefox. When I tried to change this it would not let me edit the default URLs. I had to add entirely-new versions of Google and DuckDuckGo, with custom names and stripped-down URLs in order to avoid the tagging.
No doubt it is revenue-related, but it's also a privacy problem.
Your question is assuming they're not already locking down as many of the 50 other ways as possible. Yes there are other bad things but that doesn't mean we should add #51 to that list.
I suppose it tells them you searched with the address/search bar instead of navigating to the search website. But I'm not sure why you would care about that.
Firefox makes you jump through hoops too. To enable the UI for adding custom search engines you need to set the undocumented preference "browser.urlbar.update2.engineAliasRefresh" to true.
This is not really true. The about:config flag you mentioned does add a button in the Settings page allowing the addition of custom search engines, but that's only because the intended method for adding search engines is different. The normal way doesn't require setting anything in about:config, but it might be a little hidden (still found it on my own though, so I dunno).
The regular way is to visit the homepage for the search engine you want to add and click the URL bar. This will show the usual search drop-down with the "This time, search with:" row at the bottom. If you're on the homepage for a search engine which hasn't been added to Firefox, there will be an additional button on that row allowing you to add the site as a search engine, which will make it accessible from the regular settings page like every other search engine.
I meant changing it in Preferences though, and not a drop-down like it used to be. You can add completely new engines, change defaults, and even give them keywords for quick searches without any undocumented change.
That said, keyword searches are awesome and I use them for a whole lot of things, including effectively custom search engines. I have keyword searches against, e.g., internal confluence docs so I only have to enter "con <thing I'm searching for>" and firefox will load the confluence search page, or "people <name>" to bring up our internal phonebook with a search for the employee. I don't think I've ever needed to add my own entirely custom search engine to the browser.
(My impression is that the feature is hidden behind a setting because it's half-baked and not yet ready to replace opensearchdescription xml, add-ons, and bookmark keywords as the official way to add search engines.)
If you were a government party with subpoena power, you'd think the internet was made of tubes. You'd have no idea how tech works, and only rubber stamp things tech companies provide you. Otherwise, you'd be over qualified and too focused on things other than raising money, kissing babies while stealing their lollipops.
To be fair to some of my former colleagues in government, there are some folks who do know about tech in Congress and smattered across federal agencies and the White House. While politicians themselves may not know how the internet works, if they listen to their staffers (which many do on the actual technical part of a topic if not the political or other implications of an issue), they are probably at least somewhat informed.
Kagi on Firefox requires an extension, which is ridiculous. I am about to find a more user friendly browser. Session, bookmarking and history search haven’t seen any meaningful improvement in 15+ years.
Maybe it's changed, but last time I tried to set my Searx instance as a default search provider, it involved rolling my own search provider extension for it.
