iCloud does do something, but after how many years all it seems to be is a relentlessly needy and disruptive prompt to reenter the password. It's like a car that never seems to go anywhere but always has a dead battery, you stop thinking of it as a vehicle and instead think of it as something you have to connect a battery charger to. It's originally intended useful function is entirely obscured by it's time-consuming annoyance.
One could make a list of all the serious shortcomings in Apple's products, that Apple needs to address. Instead this stuff goes on year after year. Blackberry was once a large confident company with these sorts of unaddressed shortcomings. Where are they now?
Whenever my students pointed out something annoying or useless, or an unmet but obvious need in software, computers or their phones, I'd tell them, "That's a billion dollars on the table waiting for you to come up with a solution and pick it up." And about the companies that never improved the important critical things....'they're just sitting in the middle of road blinking...they'll get run over never understanding what happened.'
Imagine a pop up message when you log on, (not it's own step with it's own delay), but just there on the screen, "iCloud, has backed up x number of your files, cleaned up junk mail on all your devices, Is it OK for iCloud to add to your Mail preferences these senders as spam to be deleted......? These music tracks that you've listened to more than 4 times in the past week will be downloaded to your iPhone so they will play without needed to use cellular data limits and delays...." and check boxes next to all of this, no I don't want to consider XYZ to be spam (even if I immediately delete almost all their messages,) and no I don't want MilliVanilli downloaded, (I only played it four times as a joke....)
Seems pretty obvious doesn't it? The iPhone was pretty obvious before there was an iPhone, Dick Tracy had one for 50 years. So why did it take Apple? Because what was obvious to Dick Tracy for 50 years wasn't obvious at all to the telecom companies making flip-phones and Blackberries. Think of your interaction with iCloud: it's just an annoyance asking for a password. What does it actually do?