Earlier quoted context omitted.
I have eight options available to me in mobile safari other than using bookmarks to use any search engine that exists. It is easy to conceive of reasons why a company would not want to enable native UI elements to rely on external services without having vetted those services or established a relationship with them for recourse in the event of issues. It is harder--though not impossible--to conceive of ways to avoid…
That doesn't make sense. Why would someone who knows how to find a different search engine, change the setting be part of the group of people who are new or otherwise clueless? Apple should provide the option.
I have to assume you're not trolling, and really can't conceive of an entire large category of people who might, in response to a Facebook post, follow step-by-step instructions to change their default search engine without understanding the ramifications thereof, or how to change it back.
There are more people in that category than in the category of people who change their default search engine for good reason, knowing that it may deliver a less-optimal experience than Google under some circumstances.