The only benefit is for people to try to things the way they do it on a different platform. It's not necessary.
You clearly have absolutely no idea about what a file manager is and what it is used for, so it's no surprise that you think that it's not necessary.
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Hey guys I don't mean to sound like a newb, but what is benefit of a file manager? Why do people say iPhones need one? What are circumstances where I would need one?
Any proper OS needs a file manager and it's purpose is, as its name suggests "managing files stored in the device".
In the current version of iOS, there isn't a common place where apps can write to or read from, so there is 0 data sharing between different apps.
For example you can't download a file, edit it with another app, and then send it as an attachment via email or open up in another app without having a separate copy of it in each app you used in the process. Also, since the apps themselves need to support the "open in..." feature in order to be able to send files to another apps (which should also have been registered as an app that can open that file in the OS), in some cases you simply can't transfer a file between apps without the help of another app such as Documents or GoodReader that can act as a hub.
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I'm pointing out that the competition can't do this natively either so what are you comparing iOS to? a desktop PC?
Does he need to compare it with another platform? Do you think that a file manager is a feature that's so advanced that only desktop platforms can handle it?
Android's file manager options are not perfect either but at least they solve some of the problems. It's certainly better than nothing.
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iCloud Drive should alleviate a lot of this so you can have 1 place to store all your documents that any app can access.
Well, since it will only work for things uploaded to the Cloud, it won't alleviate much. The feature Apple added in 8.0 to solve the file sharing issue is the Extensibility API. But as always, it will be up to devs to support it so it won't work in all apps. But considering that Apple will never add a file manager to the OS, this will be the closest thing we'll have to a file manager.