Apple have rejected apps in the past that do nothing more than point to a website. A common way to get around that is to implement a feature in native code, e.g. a banking app that points to the website, but has native mapping functionality for finding branches. I am not sure, but I think it's now covered under clause 12.3[1] of the guidelines[2].

1. Apps that are simply web clippings, content aggregators, or a collection of links, may be rejected.

2. https://developer.apple.com/appstore/resources/approval/guid...