Previously, Apple specifically prohibited charging more though AppStore for services that are available to be purchased elsewhere. I'm not in the mood to sift though current version of Apple's legalese, but I'd be surprised if they dropped this requirement, that'd be very uncharacteristic of them.
they didn't prohibit charging more for App Store purchases, they prohibited mentioning it in the app. i.e, you cannot mention something like 'purchase this in-app product for $3 cheaper on our website'.
To be more specific, previously they prohibited telling about any other ways to buy elsewhere:
"Apps and their metadata may not include buttons, external links, or other calls to action that direct customers to purchasing mechanisms other thanuse in-app purchase, except as set forth ...",
And that includes sending promotional emails if said emails were gathered via app.
