[nottorp]

You have functionality that is overlapping with something provided by Apple.

It's possible they will find reasons to reject your app indefinitely.

[agos]

if that is so they could just say that they reject the app because it replicates built in functionality - it's a well known cause for rejection

[nottorp]

They could be A/B testing.

Or more likely, Apple reviewers aren't paid so well and have 3 minutes to review each submission so they just reject for the first reason that comes up.