Again, it sounds like you're just assuming "Oh, they could never do something that stupid, of course that's allowed." When it looks like that's exactly why apple is rejecting apps. The external authentication/creating accounts. And that is why everyone is saying what apple is doing is stupid and going too far.

I'll give you another quote from the dropbox forums.

Apple is rejecting apps for allowing people to create a free account that may be updated later. Simple as that. And I think the reason you deny that so fiercely is because you realize how stupid that is

I'll admit, i don't have a version of the dropbox SDK to check, but i'm going by what the dropbox developers are saying

I find it hard to believe i'm misinterpreting those quotes that badly. Because that sounds like the problem is "creating accounts"

The issue was definitely the ability to sign up for a free account. Just read apple's rejection notice that was posted

When a user creates an account through the mobile link given, they are not upsold. There are no links to purchase a pro account. They simply enter account details, then they have a free account. No purchasing of any kind goes on in the places where the app links. Apple has stated that this is a problem because of the fact that they can later turn this account into a paid subscription, and apple won't get a cut. Which seems like a giant overreach to me.

Dropbox's statement confirms this

The reason the new SDK is fine is that it removes the ability for users to sign up for a dropbox account. If you don't have an account, you're just supposed to figure out on your own that you need to go to dropbox.com and register... And that's stupid. Apple has gone way too far with this one.

Modifying your analogy

Your store lets people come in and play games against each other. Someone comes in and says "Hey, you know, this game can be better if you go to this website and read the strategy there." You kick him out of the store and ban him from ever mentioning the website, because it happens to sell cards on an unrelated section of the website, and selling cards is banned in your store.

That is what apple is doing here. An app has dropbox integration as a feature. The user clicks on that integration and is prompted for a dropbox user name and password. There is also a button if the user does not have a dropbox account. If that button is clicked the app checks to see if the dropbox app is installed, and if not, gives them the url to register for dropbox, which is opened in Safari. This registration is completely free. Apple bans the app because the user could possibly use that dropbox url to make account and then later pay for dropbox pro and apple won't get a cut on that.

This is a major difference between an app skirting the "selling premium content" rule by linking to a url, and an app linking to a registration for a free account that has optional paid extras. Cause i'm pretty sure Apple is now saying that no app is allowed to link to google registration, facebook registration, or anything... That seems pretty absurd to me

Yeah, not really getting the whole uproar here...

The terms quoted are pretty much necessary for any site that allows user submitted content. That's the way copyright law works. If they want to display something on a webpage, they need a license to do it. If they want to convert a word document into a .pdf, that's a derivitave work. Same with showing you a thumbnail of the image you uploaded. I guarantee that 95% of the sites out there have a similar clause in their terms of service. For instance: just take a look at slashdot's own terms of service. Click that terms button down at the bottom of the page and what do you get:

submitting user retains ownership of such Geeknet Public Content; with respect to publicly-available statistical content which is generated by the site to monitor and display content activity, such content is owned by Geeknet. In each such case, the submitting user grants Geeknet the royalty-free, perpetual, irrevocable, non-exclusive, transferable license to use, reproduce, modify, adapt, publish, translate, create derivative works from, distribute, perform, and display such Content (in whole or part) worldwide and/or to incorporate it in other works in any form, media, or technology now known or later developed, all subject to the terms of any applicable license

Looks very similar, doesn't it...

My main issue with that is viewing this as a private person to person conversation. These are emails that are sent to a completely anonymous email address that the sender has no idea what's going to happen to them.

Say I make a craigslist ad that says, "Hey, I'm looking for sex, call me at +4790369389, and you call that number, and it goes to A loudspeaker that broadcasts your voice to the public. You call that number and yell out that you're looking for sex, and here's your name and email. Am I now liable for broadcasting your public information to the world, or is that your own damn fault for not realizing what that number did.

So what if i make an email address that forwards your email verbatim to an email list? Is that the same, or do you expect more privacy from an anonymous email address than an anonymous phone number?

Look, I have no problem with expecting privacy on person to person conversations. However, I have a very hard time considering an email sent to a completely anonymous email address with which you have had no prior correspondence to be a private person to person conversation.