They absolutely could control it - they could remove your app from the store if you broke your contract with them.No, Apple recently changed their rules to make it clear communication with users was OK. Something that they could never actually control, they just made it tactilely acceptable. They've also never prohibited third party processing outside of the store because that would be weird.
You still can't even mention third party processing in the app, which seems to be the intention of this law
The difference is some regulatory bodies are now saying that term of the contract is not legal.