> What kind of advantage does it give to the general user, who flaunts the fact you can do that on android?

As a member of one segment of the cellphone user population, I'll say none, really.

The ability to root your phone, IMHO, simply makes it yet another device that sucks up admin time.

Life is too short. This is the major reason I'm a participant in Apple's walled garden. I don't want to mess about more than necessary with a device that I regard as a tool. If my hammer required admin time, I'd dump it.

Well, for starters: xposed gave me a LOT of options to customize every aspect of my phone. Statusbar tweaks, screen brightness tweaks, deeper tasker integration, to name a few... for a tech savvy person with too much time on their hands it is heaven to be able to customize your phone so much more than what is initially "allowed".

But is any of it essential? Those all seem like “nice to have” features instead of something major.

...isn't the vast majority of a smartphone just a collection of "nice to have"s?

Everyone values features differently. If my valuations aren't in line with yours, what makes yours more major?

Backups, for starters. Personally I value being able to restore the software to a known state in case something happens. Not having any way to back up my data was kind of a deal breaker otherwise.

Firewalling traffic and tunneling also requires root. I believe it is a popular way to block ads and analytics, either with a hosts file or iptables.

iPhones can be backed up to iTunes or iCloud or both.