Safari Webkit Feature Flags

On my iPhone, at

SETTINGS>SAFARI>FEATURE FLAGS>WEBKIT FEATURE FLAGS there are various things, written in Geek, some turned on, some turned off. I have looked online, including in the Apple Forum, trying to find out what these are for. All I can find are two things: 1) reference to a no-longer-included Experimental Apps menu; and 2) instructions for developers. (Note to Apple: Don't include a typical form-letter-like answer that has no relevance to my query, please. Does anybody actually read the questions, or do they all go to either AI or some person in India who has to use a script?) My first guess is that the purpose of these "flags" is to let me know if apps within various categories--which, I presume I would choose to be informed of by choosing <On>--are being experimented with and are available to try. Personally, I would never do that, as something might get screwed-up, or there might be some security risk; so, I would just turn them all off, as they would serve me no purpose. BUT, if my assumption is wrong, is there a reason why what appears to be the default settings are best, or why I might want to change them (ironically, when I clicked on the search suggestion about that, I got the same above-mentioned useless search results as when I searched "iphone webkit feature flags", nothing about which flags to switch on or off)?