My app is a sync solution (imagine dropbox). The user needs to sign in to access the app\'s features, and if he does not have any account already created, he can sign up.
I recently spoke to an Apple Rep over the phone in regards to an app of mine that was also accused of violating clause 17.2.
I explained to him that the email would be used for password recovery, monitoring transactions within the marketplace, and managing any inappropriate behavior (such as users uploading offensive or copyrighted content). The rep responded, "Sir, the clause states 'Apps that require users to share personal information, such as email address and date of birth, in order to function will be rejected'. I cannot allow you to require your users to submit their emails if its not account-based". He did not seem to understand that the emails are account-based for the very sole purpose of security.
I did mention to him that Instagram and Facebook alike require logins at startup. He simply replied, "Yes but those apps are entirely account-based."
Honestly, I felt he was blindly following Apple's Guidelines ("Because that's what it says we must strictly follow!"). He had little understanding of how social networking apps operate, and even less understanding of the law (specifically the DMCA - on a separate issue). Explaining to them how all that works proves to be futile; they wont budge because they are asked to follow Apple's BROAD Clauses as strictly as they do.
My conclusion: I had to compromise the app's user flow such that the app's registration page can be skipped, and all other functions within its marketplace were locked to non-registered users. It makes no sense.